As an ophthalmologist preparing for post doctoral fellowship test my knowledge by asking advance level mcqs (30) on neurophthalmology
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I now have excellent source material from Kanski's Clinical Ophthalmology, Wills Eye Manual, Adams & Victor's Neurology, Bradley & Daroff's Neurology, and Harrison's Principles. I have enough to craft 30 advanced MCQs across all major neuro-ophthalmology domains. Let me now compose the full question set.
Advanced Neuro-Ophthalmology MCQs (30 Questions)
Fellowship-Level Test | Kanski • Wills Eye Manual • Adams & Victor • Bradley & Daroff • Harrison's
SECTION 1: PUPIL AND AUTONOMIC DISORDERS (Q1-6)
Q1. A 55-year-old man presents with right-sided ptosis and miosis. Cocaine 4% drops are instilled bilaterally - neither pupil dilates. Hydroxyamphetamine 1% is then applied - the right pupil fails to dilate while the left dilates normally. Where is the lesion?
- A) Hypothalamus (first-order neuron)
- B) Preganglionic (second-order) neuron
- C) Postganglionic (third-order) neuron
- D) Iris sphincter (efferent defect)
- E) Optic nerve (afferent defect)
Answer: C - Postganglionic (third-order) neuron
Rationale: Cocaine blocks reuptake of noradrenaline - failure of BOTH pupils to dilate confirms Horner syndrome (normal cocaine response is dilation). Hydroxyamphetamine releases noradrenaline from the postganglionic terminal; failure to dilate the affected eye localizes the lesion to the postganglionic (third-order) neuron (e.g., carotid dissection, cavernous sinus). If the lesion were first- or second-order, hydroxyamphetamine would still dilate the pupil because the postganglionic terminals are intact.
Q2. A patient has a fixed, dilated right pupil with a right exotropia and hypotropia, and complete ptosis. MRI with gadolinium shows no lesion. CT angiogram is reported as normal. What is the single most appropriate next investigation?
- A) Repeat MRI in 6 weeks
- B) Lumbar puncture
- C) Conventional catheter angiography (DSA)
- D) Edrophonium (Tensilon) test
- E) Pilocarpine 0.125% test
Answer: C - Conventional catheter angiography (DSA)
Rationale: A complete third nerve palsy with pupil involvement is a posterior communicating artery aneurysm until proven otherwise. CTA has a sensitivity of ~95-98% but when clinical suspicion is high (pupil-involving CN III palsy), a negative CTA is not sufficient to exclude aneurysm; DSA remains the gold standard. The Wills Eye Manual emphasizes: "Pain does not distinguish between microvascular ischemia and compression." Pupil involvement, however, strongly favors compressive (aneurysmal) pathology.
Q3. Pilocarpine 0.1% (dilute) is instilled into a unilaterally dilated pupil. The pupil constricts briskly. This finding is diagnostic of:
- A) Third nerve palsy (compressive)
- B) Pharmacological dilation (tropicamide)
- C) Adie's tonic pupil
- D) Argyll Robertson pupil
- E) Physiological anisocoria
Answer: C - Adie's tonic pupil
Rationale: Adie's tonic pupil results from postganglionic parasympathetic denervation (ciliary ganglion), leading to denervation supersensitivity. Dilute pilocarpine (0.1%) causes constriction of a supersensitive Adie's pupil but NOT a normal pupil or pharmacologically dilated pupil. A third nerve palsy will NOT show this supersensitivity until denervation is established (takes weeks to months). Pharmacological mydriasis (anticholinergic) actively BLOCKS pilocarpine constriction.
Q4. The Argyll Robertson (AR) pupil is characterized by which combination?
- A) Light-near dissociation; dilates well to mydriatics; irregular; bilateral
- B) Light-near dissociation; poor dilation to mydriatics; irregular; bilateral
- C) Light-near dissociation; poor dilation to mydriatics; round; unilateral
- D) Fixed dilated pupil; no near response; irregular; bilateral
- E) Normal light reflex; absent near response; round; unilateral
Answer: B - Light-near dissociation; poor dilation to mydriatics; irregular; bilateral
Rationale: Classic AR pupils (neurosyphilis) show: (1) light-near dissociation (absent light reflex, intact near response), (2) irregular, small pupils, (3) bilateral involvement, (4) poor dilation to mydriatics, and (5) failure to respond to atropine. The lesion is in the pretectal region. Contrast with Adie's: unilateral, dilated, dilates well to mydriatics, responds to dilute pilocarpine.
Q5. In a patient with right Horner syndrome, ipsilateral arm and neck pain, and a history of forceful neck manipulation the day prior, which artery is most likely injured?
- A) Right vertebral artery
- B) Right posterior inferior cerebellar artery
- C) Right internal carotid artery
- D) Right external carotid artery
- E) Right subclavian artery
Answer: C - Right internal carotid artery
Rationale: Internal carotid artery dissection classically presents with ipsilateral Horner syndrome (the oculosympathetic fibers travel along the internal carotid) + ipsilateral neck/facial pain, often without contralateral neurological deficit initially. Neck manipulation is a recognized precipitant. The sympathetic fibers accompanying the external carotid do not mediate the pupillary/lid response; the postganglionic fibers join the ophthalmic division of V via the cavernous sinus after following the ICA.
Q6. A relative afferent pupillary defect (RAPD) is NOT typically seen in which condition?
- A) Dense vitreous hemorrhage obscuring the retina
- B) Unilateral optic neuritis
- C) Unilateral severe glaucomatous optic atrophy
- D) Optic tract lesion (contralateral to dense field defect)
- E) Amblyopia (strabismic, profound)
Answer: E - Amblyopia
Rationale: RAPD requires a significant asymmetry in afferent input to the pretectal nuclei. Dense vitreous hemorrhage (A) can produce a mild RAPD; optic neuritis (B) and glaucomatous atrophy (C) produce clear RAPDs. A left optic tract lesion produces right homonymous hemianopia AND a contralateral (right) RAPD because more nasal decussating fibers from the right retina are interrupted. Amblyopia, even when severe, produces NO or only a minimal RAPD because the ganglion cell layer is relatively preserved - this is a classic teaching point distinguishing amblyopia from organic optic neuropathy.
SECTION 2: OPTIC NERVE & DISC (Q7-12)
Q7. A 30-year-old woman presents with acute painful loss of vision in her right eye. There is a right RAPD, central scotoma, and normal-appearing optic disc on fundoscopy. Visual evoked potentials show prolonged P100 latency. MRI brain shows periventricular T2 hyperintensities. What is the most appropriate immediate management?
- A) Oral prednisolone 1 mg/kg/day for 14 days
- B) IV methylprednisolone 1 g/day for 3 days
- C) Interferon beta-1a intramuscularly
- D) Natalizumab infusion
- E) Urgent neurosurgical referral
Answer: B - IV methylprednisolone 1 g/day for 3 days
Rationale: The Optic Neuritis Treatment Trial (ONTT) established that IV methylprednisolone (1 g/day x 3 days followed by oral taper) hastens visual recovery but does NOT improve final visual outcome. Oral steroids alone (option A) INCREASED the rate of recurrence in ONTT and are contraindicated as sole treatment for acute optic neuritis. The MRI findings suggest a high risk for MS conversion, making early treatment appropriate. Option A is specifically contraindicated per ONTT findings.
Q8. Papilledema is reliably distinguished from pseudopapilledema (optic disc drusen) by which single finding?
- A) Presence of spontaneous venous pulsations
- B) Blurring of disc margins
- C) Obscuration of vessels at the disc margin
- D) B-scan ultrasound showing hyperreflective foci
- E) Visual acuity reduction
Answer: C - Obscuration of vessels at the disc margin
Rationale: In true papilledema, swollen nerve fiber layer tissue physically obscures the blood vessels as they cross the disc margin - this does NOT occur in pseudopapilledema or disc drusen. Spontaneous venous pulsations (A) are ABSENT in raised ICP (their presence virtually excludes papilledema), but their absence is non-specific. Disc drusen on B-scan show hyperreflective foci (D), confirming pseudopapilledema. The key discriminating sign clinically is vessel obscuration. In drusen, vessels remain visible coursing over the elevated disc surface.
Q9. A 65-year-old woman with a 3-day history of jaw claudication, scalp tenderness, and ESR 95 mm/hr develops sudden painless vision loss in her right eye. Fundoscopy reveals a pale, swollen optic disc with splinter haemorrhages. What is the most appropriate immediate action?
- A) Start aspirin 300 mg and arrange urgent temporal artery biopsy
- B) Start high-dose oral prednisolone immediately, then arrange biopsy
- C) Arrange emergency MRI before starting steroids
- D) Instil pilocarpine and refer to neurology
- E) Await biopsy result before starting treatment
Answer: B - Start high-dose oral prednisolone immediately, then arrange biopsy
Rationale: Giant cell arteritis (GCA) causing arteritic AION is an ophthalmological emergency. Treatment must NOT be delayed for biopsy - the contralateral eye is at 25-50% risk of involvement within days without treatment. Oral prednisolone 60-80 mg/day (or IV methylprednisolone 1 g/day if vision already significantly affected) must start immediately. Temporal artery biopsy remains valid for up to 2-4 weeks after steroid initiation. ESR, jaw claudication, scalp tenderness + disc pallor = classic A-AION from GCA.
Q10. Non-arteritic AION (NA-AION) is associated with which disc feature that predisposes to the condition?
- A) Large cup-to-disc ratio (C:D > 0.6)
- B) Disc drusen
- C) Small cup-to-disc ratio ("disc at risk" - crowded disc)
- D) Tilted disc
- E) Bergmeister's papilla
Answer: C - Small cup-to-disc ratio ("disc at risk")
Rationale: The "disc at risk" in NA-AION is characteristically a small disc with a small or absent physiological cup (C:D ratio < 0.2). This crowded disc has little room for axonal swelling; compartment syndrome-like ischemia occurs in the posterior ciliary artery territory during episodes of systemic hypotension or nocturnal hypotension. The fellow eye of NA-AION patients almost invariably shows the same small crowded disc configuration. This contrasts with A-AION (GCA), where disc structure is not the key predisposing factor.
Q11. In Leber Hereditary Optic Neuropathy (LHON), which mitochondrial DNA mutation accounts for the majority (~70%) of cases?
- A) m.3460G>A (ND1 gene)
- B) m.14484T>C (ND6 gene)
- C) m.11778G>A (ND4 gene)
- D) m.8993T>G (ATP6 gene)
- E) m.3243A>G (tRNA-Leu gene)
Answer: C - m.11778G>A (ND4 gene)
Rationale: The three primary LHON mutations are m.11778G>A (ND4, ~70% worldwide), m.3460G>A (ND1, ~15%), and m.14484T>C (ND6, ~15%). The 14484 mutation has the best prognosis for spontaneous recovery (~50%). LHON predominantly affects young males (maternal inheritance via mitochondrial DNA but male predominance due to nuclear genetic modifying factors). Idebenone is the only approved treatment. Option D (m.8993) causes NARP/Leigh syndrome, not LHON.
Q12. A patient with bilateral sequential painless optic neuropathy, normal MRI brain, and no systemic risk factors is found to have very low serum vitamin B12. The pattern of visual field loss most characteristic of nutritional/toxic optic neuropathy is:
- A) Altitudinal defect
- B) Cecocentral scotoma
- C) Junctional scotoma
- D) Bitemporal hemianopia
- E) Monocular temporal crescent defect
Answer: B - Cecocentral scotoma
Rationale: Toxic and nutritional optic neuropathies preferentially affect the papillomacular bundle (the axons subserving central and paracentral vision that arise from macular ganglion cells). This produces a characteristic cecocentral scotoma - a scotoma connecting the blind spot (cecum) to the point of fixation. Causes include B12 deficiency, folate deficiency, tobacco-alcohol amblyopia, ethambutol, chloramphenicol, and methanol. Altitudinal defects characterize AION; bitemporal hemianopia localizes to the chiasm.
SECTION 3: VISUAL PATHWAYS & CORTEX (Q13-17)
Q13. A patient has a complete right homonymous hemianopia with macular sparing. Where is the lesion most likely located?
- A) Right optic tract
- B) Left optic radiation (Meyer's loop)
- C) Left primary visual cortex (calcarine cortex)
- D) Left optic tract
- E) Chiasm (posterior)
Answer: C - Left primary visual cortex (calcarine cortex)
Rationale: A complete homonymous hemianopia affects the contralateral visual field; right hemianopia = left hemisphere lesion. Macular sparing is characteristic of occipital lobe (cortical) lesions because: (1) the macular cortical representation is large and has dual blood supply (middle and posterior cerebral arteries), and (2) the macular fibers have bilateral representation. Optic tract lesions (D) produce incongruous homonymous hemianopias WITHOUT macular sparing and are associated with contralateral RAPD.
Q14. A "pie in the sky" visual field defect (superior homonymous quadrantanopia) localizes the lesion to which structure?
- A) Optic tract
- B) Parietal optic radiation
- C) Meyer's loop (temporal optic radiation)
- D) Dorsal calcarine cortex
- E) Lateral geniculate nucleus
Answer: C - Meyer's loop (temporal optic radiation)
Rationale: Meyer's loop comprises the inferior optic radiation fibers (subserving the superior visual field) that sweep anteriorly around the temporal horn of the lateral ventricle before coursing posteriorly. A temporal lobe lesion (e.g., temporal lobectomy, herpes encephalitis) interrupts Meyer's loop, producing a contralateral superior homonymous quadrantanopia - the classic "pie in the sky" defect. The parietal radiation carries superior fibers, and its damage produces an inferior quadrantanopia ("pie on the floor").
Q15. Bilateral damage to the primary visual cortex (V1) with blindness, yet the patient denies visual loss and confabulates visual experiences. This syndrome is called:
- A) Charles Bonnet syndrome
- B) Anton syndrome
- C) Balint syndrome
- D) Riddoch phenomenon
- E) Visual anosognosia with phantom limb equivalent
Answer: B - Anton syndrome
Rationale: Anton syndrome (cortical blindness with denial of blindness) results from bilateral occipital lobe infarction, typically from bilateral posterior cerebral artery territory strokes. The patient is cortically blind but vigorously denies it, confabulating visual descriptions of the environment. Charles Bonnet syndrome (A) involves formed visual hallucinations in patients with impaired vision who RETAIN INSIGHT. Balint syndrome (C) involves optic ataxia, ocular apraxia, and simultanagnosia from bilateral parieto-occipital damage.
Q16. A patient presents with inability to perceive motion (visual motion blindness) following bilateral damage to a specific cortical area, yet static vision is preserved. Which cortical area is damaged?
- A) V1 (primary visual cortex)
- B) V2 (secondary visual cortex)
- C) V4 (color processing)
- D) V5/MT (middle temporal area)
- E) V3 (dorsal stream)
Answer: D - V5/MT (middle temporal area)
Rationale: Area V5 (also called MT, middle temporal) is the cortical motion-processing area in the dorsal "where" stream. Bilateral V5 damage causes akinetopsia - the inability to perceive visual motion, with preserved form and color vision. Patients describe moving objects as a series of frozen still images; they cannot judge the speed of a car or see liquid pour smoothly. V4 damage produces achromatopsia (color blindness with preserved motion and form). This dissociation demonstrates the modular organization of visual cortex.
Q17. A junctional scotoma (ipsilateral central scotoma + contralateral superior temporal defect) localizes to which anatomical structure?
- A) Retrochiasmal optic nerve
- B) Posterior optic nerve/anterior chiasm junction
- C) Optic tract
- D) Lateral geniculate nucleus
- E) Optic radiation
Answer: B - Posterior optic nerve/anterior chiasm junction
Rationale: The junctional scotoma of Traquair results from a lesion at the junction of the optic nerve and optic chiasm. The inferior nasal fibers from the contralateral eye loop anteriorly into the ipsilateral optic nerve (Wilbrand's knee) before decussating - damage here produces ipsilateral optic nerve dysfunction (central scotoma/RAPD) AND contralateral superior temporal visual field loss. Classic causes include pituitary tumors, meningiomas, and craniopharyngiomas compressing at this junction.
SECTION 4: EYE MOVEMENT DISORDERS (Q18-23)
Q18. A 45-year-old MS patient has diplopia on rightward gaze. Examination shows: on right gaze - right eye abducts fully with nystagmus, left eye fails to adduct. On left gaze - both eyes move normally. Convergence is intact. Where is the lesion?
- A) Right PPRF (paramedian pontine reticular formation)
- B) Right medial longitudinal fasciculus (MLF)
- C) Left MLF
- D) Left sixth nerve nucleus
- E) Right third nerve (partial)
Answer: C - Left MLF
Rationale: This is a left INO. INO is named for the side of the ADDUCTION DEFICIT. The left eye fails to adduct on right gaze, localizing the lesion to the left MLF (which carries internuclear fibers from the right CN VI nucleus to the left CN III medial rectus subnucleus). Convergence is intact because convergence uses a separate pathway (not through the MLF). MS is the commonest cause of bilateral INO in young patients; vascular disease causes unilateral INO in older patients.
Q19. The "one-and-a-half syndrome" results from a unilateral lesion affecting which two structures?
- A) MLF + oculomotor nucleus
- B) PPRF + ipsilateral MLF
- C) Trochlear nucleus + MLF
- D) PPRF + contralateral MLF
- E) Abducens nucleus + contralateral MLF
Answer: B - PPRF + ipsilateral MLF
Rationale: One-and-a-half syndrome combines: (1) ipsilateral horizontal gaze palsy (from PPRF lesion) = "one" gaze palsy, and (2) ipsilateral INO (from MLF lesion) = "half" (only adduction deficit on the remaining contralateral gaze). The only preserved horizontal movement is contralateral eye abduction (with nystagmus). The ipsilateral eye is completely immobile horizontally. Caused by pontine tegmental lesions (infarct, demyelination, glioma). The vertical gaze center is rostral midbrain and is spared.
Q20. Parinaud syndrome (dorsal midbrain syndrome) includes all of the following EXCEPT:
- A) Upgaze palsy with convergence-retraction nystagmus on attempted upgaze
- B) Light-near dissociation of pupils
- C) Lid retraction (Collier's sign)
- D) Downgaze palsy
- E) Convergence insufficiency
Answer: D - Downgaze palsy
Rationale: Parinaud (dorsal midbrain) syndrome from compression of the superior colliculus/pretectal region (classically by pineal germinoma, hydrocephalus, or AVM) produces: upgaze palsy with convergence-retraction nystagmus on attempted upgaze (pathognomonic), light-near dissociation (pretectal light pathway damage with intact near reflex), Collier's lid retraction sign, and convergence insufficiency/spasm. Downgaze palsy is NOT a feature - downgaze is controlled by the riMLF and bilateral pathways, and requires more extensive midbrain damage (as seen in PSP).
Q21. A 70-year-old man develops vertical supranuclear gaze palsy, axial rigidity (retrocollis), frequent falls backward, and square wave jerks on fixation. The most likely diagnosis is:
- A) Parkinson's disease
- B) Multiple system atrophy (MSA-P)
- C) Progressive supranuclear palsy (PSP)
- D) Corticobasal degeneration
- E) Huntington's disease
Answer: C - Progressive supranuclear palsy (PSP)
Rationale: PSP (Richardson syndrome, the most common phenotype) classically presents with vertical gaze palsy (especially downgaze - distinguishing it from Parkinson's), axial rigidity, falls backward (due to postural instability), and characteristic square wave jerks (small saccadic intrusions during fixation). The vertical supranuclear gaze palsy in PSP initially affects downgaze more than upgaze - a key differential from Parinaud syndrome where upgaze is primarily affected. The pathology involves tau accumulation in the subthalamic nucleus, globus pallidus, brainstem, and cerebellum.
Q22. In a patient with acute fourth (trochlear) nerve palsy, the three-step test is performed. Which sequence of findings correctly identifies a right CN IV palsy?
- A) Step 1: Right hypertropia. Step 2: Worse on left gaze. Step 3: Worse on right head tilt.
- B) Step 1: Right hypertropia. Step 2: Worse on right gaze. Step 3: Worse on right head tilt.
- C) Step 1: Left hypertropia. Step 2: Worse on left gaze. Step 3: Worse on left head tilt.
- D) Step 1: Right hypertropia. Step 2: Worse on left gaze. Step 3: Worse on left head tilt.
- E) Step 1: Left hypertropia. Step 2: Worse on right gaze. Step 3: Worse on right head tilt.
Answer: A - Right hypertropia; worse on left gaze; worse on right head tilt
Rationale: The Park-Bielschowsky three-step test:
- Step 1: Right hypertropia (paretic superior oblique = right SO; paretic right SO allows extorsion/elevation by right inferior oblique)
- Step 2: Vertical deviation INCREASES on left gaze (right SO acts as a depressor in adduction; failure to depress the adducting right eye)
- Step 3: Vertical deviation INCREASES on right head tilt (Bielschowsky test: right head tilt intorts right eye, requiring right SO/SR; with right SO paretic, only right SR compensates, pulling the right eye up = increased right hypertropia)
Q23. Nystagmus that is horizontal, direction-changing, and purely horizontal (no vertical component) is most consistent with:
- A) Vestibular neuritis (peripheral)
- B) Benign paroxysmal positional vertigo (BPPV)
- C) Gaze-evoked nystagmus from cerebellar lesion
- D) Internuclear ophthalmoplegia
- E) Congenital nystagmus
Answer: C - Gaze-evoked nystagmus from cerebellar lesion
Rationale: Gaze-evoked (gaze-paretic) nystagmus is horizontal and beats in the direction of gaze (direction-changing with gaze direction), reflecting failure of the neural integrator (cerebellum/brainstem) to maintain an eccentric eye position. Peripheral vestibular nystagmus (A) is UNIDIRECTIONAL regardless of gaze direction (fast phase away from the lesion), never purely direction-changing. BPPV (B) is positional, torsional-vertical. INO nystagmus (D) is monocular (abducting eye only). Cerebellar lesions, drug intoxication (anticonvulsants), and Wernicke encephalopathy are key causes.
SECTION 5: CRANIAL NERVE PALSIES & CAVERNOUS SINUS (Q24-27)
Q24. A patient presents with acute painful complete third nerve palsy. After urgent CT angiography is negative, conventional DSA is also negative. Which additional diagnosis must be considered?
- A) Myasthenia gravis
- B) Cavernous sinus thrombosis
- C) Posterior communicating artery aneurysm (false negative DSA)
- D) Diabetic mononeuropathy with pupil involvement
- E) Orbital apex syndrome
Answer: C - Posterior communicating artery aneurysm (false negative DSA)
Rationale: DSA has a very small but non-zero false-negative rate for intracranial aneurysms, particularly very small aneurysms or those with thrombosis. In a pupil-involving third nerve palsy with negative initial angiography, repeat angiography in 2 weeks is recommended per most guidelines. Diabetic mononeuropathy (D) classically SPARES the pupil (the ischemia affects the core of the nerve where motor fibers reside, sparing the superficially placed parasympathetic fibers). The combination of pupil involvement + pain + complete palsy demands aneurysm exclusion.
Q25. A patient with right-sided headache, proptosis, chemosis, and ophthalmoplegia affecting CN III, IV, V1, V2, and VI, with Horner syndrome, most likely has a lesion in which location?
- A) Orbital apex
- B) Cavernous sinus
- C) Superior orbital fissure
- D) Petrous apex
- E) Cerebellopontine angle
Answer: B - Cavernous sinus
Rationale: The cavernous sinus contains CN III, IV, V1, V2, VI, and the sympathetic fibers alongside the internal carotid artery. CN V2 involvement (maxillary division) distinguishes cavernous sinus lesions from superior orbital fissure lesions (which contain only V1, not V2). The orbital apex syndrome (A) involves the optic nerve (CN II) in addition to the cranial nerves in the fissure. Horner syndrome in cavernous sinus lesions results from damage to the pericarotid sympathetic plexus. Causes include thrombosis, meningioma, pituitary adenoma, and carotid-cavernous fistula.
Q26. A 60-year-old with hypertension and diabetes develops isolated left CN VI palsy. Which feature would prompt urgent neuroimaging rather than conservative management?
- A) Hypertension and age > 50
- B) Bilateral CN VI palsies
- C) History of diabetes mellitus
- D) Mild ipsilateral headache
- E) Gradual onset over one week
Answer: B - Bilateral CN VI palsies
Rationale: Isolated unilateral CN VI palsy in a diabetic/hypertensive > 50-year-old is typically microvascular (ischemic) and resolves in 3-4 months with observation. However, BILATERAL CN VI palsies are never microvascular and always warrant urgent imaging - they suggest raised intracranial pressure (CN VI has the longest intracranial course and is a "false localizing sign"), bilateral meningeal disease (carcinomatous/infective meningitis), or pontine pathology. Other red flags: associated CN VII/VIII, involvement of multiple ipsilateral nerves, papilledema, or failure to recover by 4 months.
Q27. Which of the following ocular motor nerve palsies is most commonly caused by a contralateral midbrain lesion (crossed paralysis)?
- A) CN III palsy
- B) CN IV palsy
- C) CN VI palsy
- D) Horizontal gaze palsy
- E) Vertical gaze palsy
Answer: B - CN IV palsy
Rationale: The trochlear nerve (CN IV) is the ONLY cranial nerve that decussates completely in the dorsal midbrain before exiting. Therefore, a right CN IV nuclear/fascicular lesion produces a LEFT superior oblique palsy. All other cranial nerve motor nuclei produce ipsilateral palsies (or ipsilateral gaze paresis for CN VI). This unique decussation also explains why CN IV is commonly injured by contrecoup forces at the superior medullary velum in head trauma. This is the most frequently missed localization fact in neuro-ophthalmology.
SECTION 6: OPTIC NEURITIS, DEMYELINATION & ADVANCED CLINICAL (Q28-30)
Q28. A 35-year-old woman with a history of MS presents with recurrent attacks of optic neuritis despite interferon-beta therapy. She is found to be AQP4-IgG positive. The most appropriate change in management is:
- A) Switch to natalizumab
- B) Switch to alemtuzumab
- C) Start azathioprine or mycophenolate mofetil (NMO-spectrum disorder treatment)
- D) Add monthly IV steroids
- E) Plasmapheresis monotherapy
Answer: C - Start azathioprine or mycophenolate mofetil (NMO-spectrum disorder treatment)
Rationale: AQP4-IgG (anti-aquaporin-4 antibody) positivity reclassifies this patient as neuromyelitis optica spectrum disorder (NMOSD), NOT MS. This distinction is critical because: (1) MS disease-modifying therapies (interferon-beta, natalizumab) are INEFFECTIVE or potentially HARMFUL in NMOSD, and (2) NMOSD requires specific immunosuppression (azathioprine, mycophenolate mofetil, rituximab, or newer agents like eculizumab/inebilizumab/satralizumab). The recurrent optic neuritis pattern with bilateral/simultaneous involvement and severe attacks should always prompt AQP4-IgG testing.
Q29. Which of the following is the most sensitive OCT finding for detecting early glaucomatous optic neuropathy before visual field changes become apparent?
- A) Thinning of the macular ganglion cell-inner plexiform layer (mGCIPL)
- B) Optic disc cup enlargement
- C) Peripapillary retinal nerve fiber layer (pRNFL) thinning in the inferotemporal sector
- D) Nasal RNFL thinning
- E) Superonasal pRNFL thinning
Answer: C - Peripapillary retinal nerve fiber layer (pRNFL) thinning in the inferotemporal sector
Rationale: The inferotemporal pRNFL sector is the most sensitive OCT parameter for early glaucoma detection, corresponding to the superotemporal retinal nerve fiber bundle that enters the optic disc superiorly and generates early superior arcuate visual field defects. Glaucomatous damage follows a characteristic pattern: inferotemporal > superotemporal > inferior > superior RNFL loss on OCT. Structural damage on OCT precedes detectable visual field loss by an estimated 5-8 years ("structure-function gap"). mGCIPL (A) is complementary and particularly useful for progression monitoring in moderate glaucoma.
Q30. A 25-year-old obese woman presents with 3 months of bilateral disc edema, pulsatile tinnitus, transient visual obscurations (TVOs), and headache. Visual fields show bilateral enlarged blind spots. Lumbar puncture reveals opening pressure of 32 cm H₂O with normal CSF composition. MRI shows empty sella and bilateral transverse sinus stenosis. Which medication has the strongest evidence for reducing intracranial pressure in this condition?
- A) Furosemide
- B) Topiramate
- C) Acetazolamide
- D) Dexamethasone
- E) Digoxin
Answer: C - Acetazolamide
Rationale: This is idiopathic intracranial hypertension (IIH/pseudotumour cerebri). The IIHTT (IIH Treatment Trial) - the largest RCT in IIH - demonstrated that acetazolamide (up to 4 g/day) combined with weight loss significantly improved visual field mean deviation compared to weight loss alone. Acetazolamide acts by inhibiting choroid plexus carbonic anhydrase, reducing CSF production. Topiramate (B) has carbonic anhydrase inhibitory activity and promotes weight loss, making it a second-line option, but it lacks the RCT evidence that acetazolamide has. TVOs are a marker of optic nerve compromise and demand prompt treatment to prevent permanent visual loss.
Summary Table
| Q | Topic | Answer |
|---|---|---|
| 1 | Horner - hydroxyamphetamine localization | C |
| 2 | Pupil-involving CN III - investigation | C |
| 3 | Dilute pilocarpine test | C |
| 4 | Argyll Robertson pupil | B |
| 5 | Carotid dissection + Horner | C |
| 6 | RAPD - amblyopia exception | E |
| 7 | Optic neuritis treatment | B |
| 8 | Papilledema vs drusen | C |
| 9 | GCA-AION emergency | B |
| 10 | NA-AION disc at risk | C |
| 11 | LHON mutation | C |
| 12 | Nutritional optic neuropathy field defect | B |
| 13 | Homonymous hemianopia with macular sparing | C |
| 14 | Pie in the sky defect | C |
| 15 | Anton syndrome | B |
| 16 | Akinetopsia - cortical area | D |
| 17 | Junctional scotoma | B |
| 18 | INO localization | C |
| 19 | One-and-a-half syndrome structures | B |
| 20 | Parinaud syndrome - NOT a feature | D |
| 21 | PSP diagnosis | C |
| 22 | Three-step test CN IV | A |
| 23 | Direction-changing nystagmus | C |
| 24 | Pupil-involving CN III - negative DSA | C |
| 25 | Cavernous sinus vs orbital apex | B |
| 26 | CN VI palsy - imaging indication | B |
| 27 | Crossed CN palsy | B |
| 28 | AQP4-IgG / NMOSD management | C |
| 29 | OCT in early glaucoma | C |
| 30 | IIH treatment - IIHTT evidence | C |
Sources: Kanski's Clinical Ophthalmology 10e, Wills Eye Manual 8e, Adams & Victor's Principles of Neurology 12e, Bradley & Daroff's Neurology in Clinical Practice, Harrison's Principles of Internal Medicine 22e, Localization in Clinical Neurology 8e.
As an ophthalmologist preparing for post doctoral fellowship teach me corneal dystrophies
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Now let me get the granular dystrophy section and the PPCD/CHED details, plus images:
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I now have comprehensive source material from Kanski's Clinical Ophthalmology 10e and the Wills Eye Manual covering all layers. Let me now fetch some key clinical images to include.
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I now have comprehensive textbook data and clinical images from Kanski's 10e and Wills Eye Manual. Let me deliver the full fellowship-level teaching on corneal dystrophies.
Corneal Dystrophies — Fellowship-Level Teaching
Source: Kanski's Clinical Ophthalmology 10e | Wills Eye Manual 8e | Goldman-Cecil Medicine
Definition & Key Principles
Corneal dystrophies are a group of progressive, usually bilateral, primary corneal disorders that are:
- Primarily affecting one layer of the cornea
- Inherited (mostly autosomal dominant)
- Not related to systemic disease, inflammation, or environmental factors
- Associated with varying degrees of visual impairment and corneal erosions
The IC3D (International Committee for Classification of Corneal Dystrophies) classifies them by the layer predominantly affected:
- Epithelial and subepithelial
- Epithelial-stromal (TGFBI group)
- Stromal
- Descemet membrane and endothelial
Most are AD - the key exceptions (AR): Macular dystrophy, Type 3 lattice dystrophy, and CHED2.
LAYER 1: EPITHELIAL DYSTROPHIES
1. Epithelial Basement Membrane Dystrophy (EBMD)
Also: Map-Dot-Fingerprint / Cogan Dystrophy
| Feature | Detail |
|---|---|
| Inheritance | Usually sporadic (degenerative); rare AD familial form |
| Gene | Not consistently identified; sporadic cases may not be true dystrophies |
| Histology | Thickened BM with fibrillary protein between BM and Bowman layer; deficient hemidesmosomes |
| Onset | 2nd decade; ~10% develop recurrent erosions in 3rd decade |
Signs (best seen on retroillumination or broad slit-lamp):
- Maps - diffuse grey subepithelial patches
- Dots - creamy white microcysts
- Fingerprints - whorled refractile lines
Clinical pearl: Most common anterior dystrophy. Bilateral recurrent erosions without trauma history = think EBMD. Treated the same as recurrent erosion syndrome (hypertonic saline, bandage CL, epithelial debridement, anterior stromal puncture, PTK).
2. Meesmann Epithelial Dystrophy
| Feature | Detail |
|---|---|
| Inheritance | AD |
| Gene | KRT3 or KRT12 (corneal epithelial keratins 3 and 12) |
| Histology | Irregular thickening of epithelial BM; intraepithelial cysts containing "peculiar substance" |
| Onset | First years of life; usually asymptomatic until middle age |
Signs: Myriad tiny, uniform intraepithelial vesicles maximal centrally, extending toward but not reaching the limbus (seen best on retroillumination). Usually non-progressive.
Management: Usually no treatment needed; symptomatic erosions treated conservatively.
LAYER 2: BOWMAN LAYER DYSTROPHIES (TGFBI Group - Anterior)
3. Reis-Bücklers Corneal Dystrophy (GCD Type 3 / CBD1)
| Feature | Detail |
|---|---|
| Inheritance | AD |
| Gene | TGFBI (chromosome 5q31) |
| Histology | Replacement of Bowman layer by connective tissue bands |
| Onset | Severe recurrent erosions begin in childhood |
Signs:
- Grey-white geographic subepithelial opacities, most dense centrally
- Increasing density with age forming a reticular pattern
- Reduced corneal sensation
Treatment: PTK (excimer laser); penetrating keratoplasty for advanced cases.
4. Thiel-Behnke Corneal Dystrophy (CBD2)
"Honeycomb dystrophy"
| Feature | Detail |
|---|---|
| Inheritance | AD |
| Gene | TGFBI (and at least one other locus) |
| Histology | "Curly fibres" on electron microscopy (key distinguishing feature from Reis-Bücklers) |
| Onset | Recurrent erosions in childhood |
Signs: Subepithelial opacities in a honeycomb/network of tiny rings pattern, central cornea. Less severe than Reis-Bücklers.
Differentiating Reis-Bücklers vs. Thiel-Behnke: Both are TGFBI-related Bowman layer dystrophies with childhood erosions. Thiel-Behnke shows curly fibres on EM; Reis-Bücklers shows connective tissue band replacement. Clinically Thiel-Behnke has a honeycomb pattern vs. geographic pattern in RB. Histopathology/EM may be required for definitive distinction.
LAYER 3: STROMAL DYSTROPHIES (TGFBI Group)
These three - Granular, Lattice (TGFBI type), and Avellino - are all caused by different mutations in the same gene: TGFBI (also written as BIGH3), encoding transforming growth factor-beta-induced protein (keratoepithelin).
5. Granular Corneal Dystrophy Type 1 (GCD1, Classic)
| Feature | Detail |
|---|---|
| Inheritance | AD (homozygous = more severe) |
| Gene | TGFBI - R555W mutation |
| Histology | Amorphous hyaline deposits - stain bright red with Masson trichrome |
| Between deposits | Clear stroma (key distinguishing feature) |
| Periphery | Spared - no extension to limbus |
Signs:
- Discrete white anterior stromal opacities resembling "sugar granules, breadcrumbs, or glass splinters"
- Gradual increase in number, confluence → diffuse haze → visual impairment
- Impaired corneal sensation
- Recurrent erosions uncommon
Treatment: PTK for superficial recurrences post-keratoplasty; PKP or DALK usually needed by 5th decade.
6. Granular Corneal Dystrophy Type 2 (GCD2 / Avellino Dystrophy)
"Combined granular-lattice dystrophy"
| Feature | Detail |
|---|---|
| Inheritance | AD |
| Gene | TGFBI - R124H mutation |
| Histology | BOTH hyaline AND amyloid (combined features) |
| Onset | Signs by end of first decade in heterozygotes |
Signs:
- Fine superficial opacities progressing to stellate or annular lesions
- Associated deeper linear opacities (lattice component)
- Mild recurrent erosions
Critical fellowship point: Corneal trauma accelerates progression in Avellino dystrophy. Refractive surgery (LASIK) is absolutely contraindicated - laser ablation dramatically worsens the opacification by activating abnormal TGFBI protein deposition. This is one of the most important preoperative screening pearls.
7. Lattice Corneal Dystrophy, TGFBI Type (LCD1, Classic)
| Feature | Detail |
|---|---|
| Inheritance | AD (>25 heterozygous TGFBI mutations described) |
| Gene | TGFBI |
| Histology | Amyloid - stains with Congo red, shows green birefringence under polarized light |
| Deposits | Located in stroma |
Signs:
- Refractile anterior stromal dots coalescing into a fine filamentous lattice network
- Spares the periphery (contrast with LCD2 which is more peripheral)
- Generalized stromal haze progressively impairs vision
- Recurrent erosions at end of first decade (often before stromal signs visible)
- Reduced corneal sensation
Treatment: PKP or DALK; recurrence is common post-keratoplasty.
8. Lattice Corneal Dystrophy Type 2 (LCD2 / Meretoja Syndrome / Gelsolin type)
| Feature | Detail |
|---|---|
| Inheritance | AD |
| Gene | GSN (gelsolin, chromosome 9q34) |
| Systemic | Systemic amyloidosis: cranial neuropathies (CN VII most common), peripheral neuropathy, lax skin (cutis laxa), renal involvement |
| Key difference | This is a systemic condition, not a pure corneal dystrophy |
Ocular signs:
- Sparse stromal lattice lines spreading from periphery centrally (opposite of LCD1 which spares periphery)
- Late visual impairment; erosions rare
Fellowship pearl: LCD2 (Meretoja) = gelsolin mutation + systemic amyloidosis. Cranial neuropathy (facial nerve palsy) + lax skin + corneal lattice = Meretoja syndrome. The lattice lines are less dense and more peripheral than in LCD1.
LAYER 3: STROMAL DYSTROPHIES (Non-TGFBI)
9. Macular Corneal Dystrophy (MCD)
| Feature | Detail |
|---|---|
| Inheritance | Autosomal RECESSIVE (the only common stromal dystrophy that is AR) |
| Gene | CHST6 (carbohydrate sulfotransferase 6) → defective sulfation of keratan sulfate |
| Histology | Aggregations of glycosaminoglycans (unsulfated keratan sulfate) intra- and extracellularly; stain with Alcian blue and colloidal iron |
| Geographic prevalence | Relatively common in Iceland |
Signs:
- Dense but poorly delineated (diffuse/cloudy borders) greyish-white opacities
- Centrally in anterior stroma, peripherally in posterior stroma
- No clear zone - extends to the limbus (contrast with granular which spares limbus)
- Full-thickness stromal involvement eventually
- Earliest: corneal thinning; late: thickening from endothelial dysfunction
- Early visual deterioration (end of first decade)
- Recurrent erosions very common
- Reduced sensation
Treatment: PKP. Recurrence is common post-keratoplasty.
Comparison Table: The Three Classic Stromal Dystrophies
| Feature | Granular (GCD1) | Macular (MCD) | Lattice (LCD1) |
|---|---|---|---|
| Inheritance | AD | AR | AD |
| Gene | TGFBI | CHST6 | TGFBI |
| Histology | Hyaline | GAGs (keratan sulfate) | Amyloid |
| Stain | Masson trichrome (red) | Alcian blue / colloidal iron | Congo red (+green birefringence) |
| Opacity morphology | Discrete, well-defined | Diffuse, poorly defined | Filamentous lattice lines |
| Between opacities | Clear stroma | Diffuse haze | Hazy |
| Limbus | Spared | Involved | Spared |
| Corneal thickness | Normal | Thinned (early) | Normal |
| Recurrent erosions | Uncommon | Very common | Common (early feature) |
| Onset (symptoms) | Later (3rd-5th decade) | End of 1st decade | End of 1st decade |
| Sensation | Impaired | Impaired | Impaired |
| Treatment | PKP/DALK | PKP | PKP/DALK |
10. Schnyder Corneal Dystrophy (Crystalline Corneal Dystrophy)
| Feature | Detail |
|---|---|
| Inheritance | AD |
| Gene | UBIAD1 (UbiA prenyltransferase domain-containing 1) |
| Histology | Phospholipid and cholesterol deposits (lipid metabolism disorder) |
| Systemic | Associated with systemic dyslipidaemia in some patients |
Signs:
- Central haze is the earliest and most consistent feature
- Crystals may or may not be present (term "crystalline" no longer recommended)
- Dense arcus senilis develops early
- Progresses to full-thickness stromal involvement
- Genu valgum (lipid storage) in some patients
Treatment: PTK for superficial involvement; PKP for advanced cases.
11. Central Cloudy Dystrophy of François
- Rare; AD
- Posterior stromal polygonal grey opacities with clear interstices ("crocodile shagreen-like")
- Usually nonprogressive, minimal visual impact; no treatment required
LAYER 4: DESCEMET MEMBRANE & ENDOTHELIAL DYSTROPHIES
12. Fuchs Endothelial Corneal Dystrophy (FECD)
The most clinically important endothelial dystrophy.
| Feature | Detail |
|---|---|
| Inheritance | Mostly sporadic; occasional AD; early-onset: COL8A2 mutation; late-onset (most common): TCF4 (CTG18.1 trinucleotide repeat expansion) |
| Sex | More common in women |
| Associations | Slightly increased prevalence of glaucoma (angle abnormalities) |
| Pathology | Bilateral accelerated endothelial cell loss; abnormal endothelial cells secrete irregular collagen nodules on DM |
Natural History & Signs (in order of progression):
Stage 1 - Cornea Guttata:
- Irregular wart-like excrescences on Descemet membrane
- Specular reflection: tiny dark spots disrupting regular endothelial mosaic
- Asymptomatic
Stage 2 - Stromal Edema:
- Specular reflection: "beaten metal" appearance
- Gradual central stromal edema
- Morning blurring (worse on waking, improves through day as edema evaporates)
Stage 3 - Epithelial Edema (Bullous Keratopathy):
- Microcysts → bullae formation
- Rupture of bullae = acute severe pain (nerve exposure)
- Significant vision loss
Stage 4 - Subepithelial Scarring:
- Peripheral vascularization
- Paradoxically less painful (scarring reduces nerve exposure)
Treatment:
Conservative:
- Topical NaCl 5% (hypertonic saline) drops/ointment - reduces epithelial edema
- Hair dryer at arm's length in morning
- IOP reduction (reduces endothelial stress)
Ruptured bullae:
- Bandage contact lens
- Cycloplegia, lubricants, topical antibiotics
Surgical:
- DMEK (Descemet Membrane Endothelial Keratoplasty) - gold standard; best outcomes, fastest recovery
- DSAEK (Descemet Stripping Automated Endothelial Keratoplasty) - older lamellar technique
- PKP - still used in combined disease
- Rho-kinase (ROCK) inhibitor (ripasudil/netarsudil) with prior transcorneal endothelial cryotherapy - stimulates endothelial proliferation (promising emerging therapy)
Critical surgical pearl: Pre-op CCT > 630-640 μm in a patient with guttata = significant risk of persistent corneal edema post-cataract surgery. These patients need either staged (corneal surgery first) or combined (triple procedure: phaco + IOL + DSAEK/DMEK) approach.
13. Posterior Polymorphous Corneal Dystrophy (PPCD)
| Feature | Detail |
|---|---|
| Forms | PPCD1, PPCD2, PPCD3 |
| Inheritance | AD |
| Genes | PPCD1: VSX1; PPCD2: COL8A2; PPCD3: ZEB1 |
| Pathology | Metaplasia of endothelial cells → acquire epithelial-like properties |
| Associations | Iris abnormalities, glaucoma, Alport syndrome (renal disease + ocular abnormalities) |
Signs:
- Subtle vesicular, band-like, or diffuse endothelial lesions
- Usually asymptomatic and found incidentally
- Rarely causes corneal decompensation
Treatment: Usually NOT required. Monitor for glaucoma.
14. Congenital Hereditary Endothelial Dystrophy (CHED)
| Feature | CHED1 | CHED2 |
|---|---|---|
| Inheritance | AD (may overlap with PPCD) | AR |
| Gene | Chromosome 20 (locus) | SLC4A11 (bicarbonate transporter) |
| Onset | First 1-2 years | Neonatal |
| Symptoms | Photophobia and watering common | Photophobia usually absent |
| Nystagmus | Less common | More common |
| Severity | Less severe | More severe |
| Association | - | Harboyan syndrome (CHED2 + late-onset sensorineural deafness) |
Signs: Diffuse corneal clouding and thickening (blue-grey ground-glass appearance). Visual acuity may surpass what is expected from the corneal appearance.
Treatment: Lamellar or penetrating keratoplasty. Early surgery recommended to prevent amblyopia.
Harboyan syndrome = CHED2 (SLC4A11 mutation) + progressive sensorineural deafness. Important for genetic counseling.
MASTER SUMMARY TABLE - All Corneal Dystrophies
| Dystrophy | Layer | Inheritance | Gene | Histology/Stain | Key Clinical Feature |
|---|---|---|---|---|---|
| EBMD (Cogan) | Epithelial | Sporadic/AD | - | BM thickening; deficient hemidesmosomes | Maps, dots, fingerprints; recurrent erosions |
| Meesmann | Epithelial | AD | KRT3/KRT12 | Intraepithelial cysts | Myriad uniform vesicles; not reaching limbus |
| Reis-Bücklers | Bowman | AD | TGFBI | Connective tissue bands replace Bowman | Geographic subepithelial opacities; severe childhood erosions |
| Thiel-Behnke | Bowman | AD | TGFBI | "Curly fibres" on EM | Honeycomb opacities; less severe than RB |
| Granular Type 1 | Stroma | AD | TGFBI | Hyaline / Masson trichrome (red) | Discrete white "breadcrumb" opacities; clear stroma between; no erosions |
| Granular Type 2 (Avellino) | Stroma | AD | TGFBI | Hyaline + amyloid | Stellate opacities; LASIK contraindicated |
| Lattice Type 1 | Stroma | AD | TGFBI | Amyloid / Congo red (+green birefringence) | Refractile lattice lines; early erosions; spares periphery |
| Lattice Type 2 (Meretoja) | Stroma | AD | GSN (gelsolin) | Amyloid in stroma | Systemic amyloidosis; CN VII palsy; lattice from periphery inward |
| Macular | Stroma | AR | CHST6 | GAGs / Alcian blue + colloidal iron | Diffuse ill-defined opacities; extends to limbus; earliest thinning |
| Schnyder | Stroma | AD | UBIAD1 | Phospholipid + cholesterol | Central haze; dyslipidaemia association; arcus |
| Fuchs FECD | Endothelial/DM | Sporadic/AD | COL8A2; TCF4 | Cornea guttata (DM excrescences) | Morning blurring; beat-metal endothelium; DMEK treatment |
| PPCD | Endothelial | AD | VSX1/COL8A2/ZEB1 | Endothelial metaplasia | Incidental; vesicular/band lesions; Alport association |
| CHED1 | Endothelial | AD | Chr.20 | DM thickening | Neonatal-1st year clouding; photophobia |
| CHED2 | Endothelial | AR | SLC4A11 | DM thickening | Neonatal clouding; nystagmus; Harboyan syndrome |
High-Yield Fellowship Pearls
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TGFBI gene encodes keratoepithelin - mutations cause: Reis-Bücklers, Thiel-Behnke, Granular 1, Granular 2 (Avellino), Lattice 1. Different point mutations in the SAME gene cause different clinical phenotypes.
-
AR dystrophies: Macular (CHST6), Lattice type 3, CHED2 (SLC4A11). Everything else is usually AD.
-
Staining memory aid - "GML": Granular = Masson trichrome (red); Macular = Alcian blue; Lattice = Congo red (green birefringence under polarized light).
-
LASIK contraindication: Avellino (GCD2) - trauma/laser dramatically accelerates opacity. All TGFBI dystrophies warrant caution; Avellino is absolute contraindication.
-
Meretoja (LCD2) is a systemic disease, not a pure corneal dystrophy - remember CN VII palsy + lax skin + renal amyloid.
-
Macular dystrophy is the most severe stromal dystrophy (AR, earliest symptoms, full thickness, extends to limbus, earliest visual impairment).
-
Fuchs endothelial: CCT > 630-640 μm = risk with cataract surgery. Morning blurring (hypotonic sleep cornea) is the hallmark. DMEK > DSAEK for outcomes.
-
CHED2 + deafness = Harboyan syndrome (SLC4A11).
-
PPCD - endothelial cells behave like epithelium (metaplasia); associated with Alport syndrome and glaucoma.
-
Recurrence after keratoplasty is common in Granular, Macular, and Lattice dystrophies because the genetic defect persists in the host keratocytes which repopulate the graft stroma.
Sources: Kanski's Clinical Ophthalmology 10e, p.265-276; Wills Eye Manual 8e, Ch.4.25, p.273-281
As an ophthalmologist preparing for post doctoral fellowship test my knowledge by asking advance level mcqs (30) on corneal dystophy
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I have thorough source data from Kanski's 10e and Wills Eye Manual. Now I'll craft 30 high-quality fellowship-level MCQs across all dystrophy categories.
Advanced Corneal Dystrophies — 30 Fellowship MCQs
Source: Kanski's Clinical Ophthalmology 10e | Wills Eye Manual 8e | Goldman-Cecil Medicine
SECTION 1: GENETICS, CLASSIFICATION & IC3D (Q1–5)
Q1. According to the IC3D (International Committee for Classification of Corneal Dystrophies), which of the following groupings is INCORRECT?
- A) Epithelial and subepithelial dystrophies: EBMD, Meesmann, Lisch epithelial dystrophy
- B) Epithelial-stromal TGFBI dystrophies: Reis-Bücklers, Thiel-Behnke, Granular 1, Granular 2, Lattice 1
- C) Stromal dystrophies: Macular, Schnyder, Central cloudy dystrophy of François
- D) Descemet membrane and endothelial: Fuchs, PPCD, CHED, X-linked endothelial dystrophy
- E) Lattice type 2 (Meretoja/gelsolin) is classified under epithelial-stromal TGFBI dystrophies
Answer: E
Rationale: Lattice type 2 (Meretoja syndrome) is caused by a mutation in the GSN gene (gelsolin), NOT TGFBI. It is classified separately as a stromal dystrophy and is a systemic amyloidosis rather than a true TGFBI-associated dystrophy. All of A-D are correctly stated. The TGFBI group specifically contains dystrophies caused by mutations in the TGFBI gene on chromosome 5q31 - encoding keratoepithelin (transforming growth factor beta-induced protein).
Q2. A 28-year-old Korean patient with bilateral central anterior stromal opacities presents for LASIK evaluation. Slit-lamp shows fine superficial stellate opacities with some deeper linear lesions. Genetic testing reveals an R124H mutation. Which statement about this patient's management is most accurate?
- A) LASIK is safe as long as residual stromal bed exceeds 250 μm
- B) Surface ablation (PRK) is the preferred alternative to LASIK
- C) Refractive surgery is absolutely contraindicated
- D) SMILE procedure avoids the risk as it does not use excimer laser
- E) Spectacle correction is unnecessary since visual acuity is unaffected until 5th decade
Answer: C
Rationale: R124H mutation in TGFBI = Avellino dystrophy (GCD2). Corneal trauma, including any refractive surgery (LASIK, PRK, SMILE, or any excimer ablation), dramatically accelerates deposition of the abnormal keratoepithelin protein, causing rapid and severe worsening of corneal opacification. This is an absolute contraindication to all forms of refractive surgery. The mechanism involves laser-induced activation of TGFBI protein synthesis in keratocytes. Multiple case reports have documented devastating visual outcomes after LASIK in Avellino dystrophy - this is one of the most important preoperative screening points in refractive surgery practice.
Q3. Which pair correctly matches the corneal dystrophy to its inheritance pattern?
- A) Macular - AD; Lattice type 1 - AR; Granular 1 - AR
- B) Macular - AR; Lattice type 1 - AD; Granular 1 - AD
- C) Macular - AR; CHED2 - AD; Lattice type 2 - AR
- D) CHED2 - AD; PPCD - AR; Fuchs - X-linked
- E) Schnyder - AR; Granular 1 - AD; Fuchs - X-linked recessive
Answer: B
Rationale: The key inheritance facts: Macular (CHST6) = AR - the only common stromal dystrophy that is autosomal recessive; Lattice type 1 (TGFBI) = AD; Granular type 1 (TGFBI) = AD. The main AR dystrophies to memorize are: Macular, Lattice type 3, CHED2 (SLC4A11), and Congenital stromal dystrophy (decorin/DCN). All TGFBI group dystrophies are AD. PPCD is AD. Fuchs is mostly sporadic with some AD cases.
Q4. A 45-year-old patient with bilateral corneal opacities is referred for genetic testing. A single-nucleotide mutation in the TGFBI gene is found at codon 555 (R555W). What is the most likely diagnosis?
- A) Lattice corneal dystrophy type 1
- B) Avellino (GCD2) dystrophy
- C) Granular corneal dystrophy type 1
- D) Reis-Bücklers dystrophy
- E) Thiel-Behnke dystrophy
Answer: C
Rationale: Specific TGFBI mutation-phenotype correlations:
- R555W → Granular corneal dystrophy type 1 (GCD1)
- R124H → Granular corneal dystrophy type 2 / Avellino
- R124C → Lattice corneal dystrophy type 1 (LCD1) - most common
- R124L → Lattice corneal dystrophy type 3A
- R555Q → Reis-Bücklers corneal dystrophy
- R124S / A546D → Thiel-Behnke dystrophy
These mutation-phenotype correlations are heavily tested at fellowship level. Remarkably, different point mutations within the same gene (TGFBI) produce phenotypically distinct dystrophies affecting different layers.
Q5. Which gene mutation is correctly matched with its corneal dystrophy?
- A) CHST6 → Schnyder dystrophy
- B) SLC4A11 → CHED2 and Harboyan syndrome
- C) COL8A2 → Macular corneal dystrophy
- D) GSN → Meesmann dystrophy
- E) KRT3 → Posterior polymorphous corneal dystrophy type 2
Answer: B
Rationale: SLC4A11 encodes a bicarbonate/sodium transporter expressed in corneal endothelium. Mutations cause CHED2 (AR, neonatal onset, severe bilateral clouding) and when associated with progressive sensorineural deafness = Harboyan syndrome. The other correct pairings are: CHST6 → Macular dystrophy (keratan sulfate sulfotransferase); UBIAD1 → Schnyder; COL8A2 → Fuchs early-onset AND PPCD2; GSN → Lattice type 2 (Meretoja); KRT3 or KRT12 → Meesmann; VSX1 → PPCD1; ZEB1 → PPCD3.
SECTION 2: EPITHELIAL & BOWMAN LAYER DYSTROPHIES (Q6–9)
Q6. A 35-year-old woman presents with painful right eye on waking. She has had multiple similar episodes over 3 years, always on opening the eyes in the morning. Slit-lamp retroillumination shows subtle map-like grey patches and fine whorled lines in the epithelium. The most likely diagnosis is:
- A) Lattice corneal dystrophy type 1
- B) Epithelial basement membrane dystrophy (EBMD)
- C) Meesmann dystrophy
- D) Recurrent erosion from prior trauma
- E) Superficial punctate keratopathy
Answer: B
Rationale: Pain on waking (as lids separate, the adhesion-deficient epithelium tears) + map-dot-fingerprint changes on retroillumination = classic EBMD (Cogan). The pathology is deficient hemidesmosomes and thickened BM with fibrillary protein deposit between BM and Bowman layer, leading to poor epithelial adhesion. The occurrence of bilateral recurrent erosions with no trauma history is the clinical hallmark. Meesmann shows uniform vesicles not reaching limbus; Lattice shows stromal lattice lines. Treatment parallels recurrent erosion syndrome: lubricants, hypertonic saline, BCL, anterior stromal puncture, or PTK.
Q7. Meesmann epithelial dystrophy is caused by mutations in KRT3 or KRT12. What do these genes encode, and which examination finding best distinguishes Meesmann from EBMD?
- A) Collagen type VIII; dendritiform epithelial lesions
- B) Corneal epithelial keratins; myriad uniform intraepithelial vesicles NOT reaching limbus
- C) Basement membrane proteins; map-like subepithelial grey patches
- D) Keratan sulfate sulfotransferase; diffuse stromal haze
- E) Corneal crystallins; subepithelial crystalline deposits
Answer: B
Rationale: KRT3 and KRT12 encode corneal epithelial keratins 3 and 12, which are specific to corneal epithelium. Mutations disrupt the keratin intermediate filament network, causing formation of intraepithelial cysts containing a "peculiar substance" on EM. The distinguishing feature from EBMD is: Meesmann shows myriad tiny, uniform-sized intraepithelial vesicles/cysts maximal centrally and extending toward but not reaching the limbus - this distribution and uniformity differs from the variable maps/dots/fingerprints of EBMD. Meesmann is usually non-progressive and rarely causes significant visual impairment.
Q8. Reis-Bücklers and Thiel-Behnke corneal dystrophies can both cause severe recurrent erosions in childhood and are both TGFBI-related. The single most reliable way to distinguish them is:
- A) Age of onset of recurrent erosions (Reis-Bücklers earlier)
- B) Slit-lamp morphology: geographic opacities vs. honeycomb pattern
- C) Electron microscopy: connective tissue bands (RB) vs. "curly fibres" (TB)
- D) Response to excimer laser PTK (Thiel-Behnke responds better)
- E) Inheritance pattern: Reis-Bücklers is AR, Thiel-Behnke is AD
Answer: C
Rationale: While slit-lamp morphology (geographic vs. honeycomb) provides a clinical clue, the definitive distinction requires electron microscopy (EM). Reis-Bücklers shows replacement of Bowman layer by connective tissue bands (fibrous collagenous material). Thiel-Behnke shows the pathognomonic "curly fibres" (sawtooth-shaped collagen fibrils) on EM. Both are AD TGFBI mutations. In clinical practice, Thiel-Behnke is generally less severe than Reis-Bücklers. EM is stated by Kanski as required for "definitive distinction from Thiel-Behnke dystrophy in some cases."
Q9. A 12-year-old presents with recurrent corneal erosions. On slit-lamp, there are grey-white geographic subepithelial opacities, most dense centrally, with reduced corneal sensation. Genetic testing reveals a TGFBI mutation at codon R555Q. What is the prognosis and preferred treatment for this condition?
- A) Excellent visual prognosis; no treatment needed as it is self-limiting
- B) Recurrent erosions managed with BCL; vision remains good lifelong
- C) Progressive opacification requiring keratoplasty; excimer PTK controls erosions and superficial recurrences
- D) Visual prognosis is good as stromal opacity is limited to Bowman layer
- E) Corneal transplant is contraindicated due to high recurrence risk
Answer: C
Rationale: R555Q = Reis-Bücklers dystrophy. It is progressive - erosions begin in childhood and opacification worsens over decades, eventually impairing vision. Excimer laser keratectomy (PTK) achieves satisfactory control in many patients and is the first-line surgical approach. Corneal transplant (PKP) is reserved for advanced opacification. Recurrence in the graft is possible. Corneal transplant is NOT contraindicated - it is a valid treatment for advanced disease. The answer is NOT E; recurrence risk exists but is not a contraindication.
SECTION 3: STROMAL DYSTROPHIES — TGFBI GROUP (Q10–16)
Q10. The classic triad used to distinguish the three major TGFBI stromal dystrophies (Granular, Lattice, Macular) involves: opacity morphology, intervening stroma appearance, and peripheral corneal involvement. Which combination is CORRECT for Granular type 1?
- A) Diffuse cloudy opacities; hazy intervening stroma; extends to limbus
- B) Filamentous lattice lines; hazy intervening stroma; spares periphery
- C) Discrete white "breadcrumb" deposits; clear intervening stroma; spares limbus
- D) Discrete white deposits; hazy intervening stroma; extends to limbus
- E) Refractile dots coalescing; clear stroma; extends to limbus
Answer: C
Rationale: The classic mnemonic for differentiating the three:
- Granular: discrete, well-defined white deposits like breadcrumbs/sugar granules; clear stroma between deposits; spares the limbus; stains red with Masson trichrome (hyaline)
- Macular: diffuse, ill-defined grey opacities; hazy intervening stroma; extends to limbus (no clear zone); stains with Alcian blue (GAGs)
- Lattice: filamentous refractile lines; hazy stroma over time; spares the periphery; Congo red positive (amyloid)
Q11. Granular corneal dystrophy type 1 (GCD1) has homozygous disease that produces a more severe phenotype. A homozygous patient with GCD1 compared to a heterozygote would show:
- A) Earlier onset and milder disease due to redundancy of normal allele
- B) Later onset, same severity
- C) Earlier onset, denser and more widespread opacities, requiring earlier keratoplasty
- D) No difference in clinical severity (dosage insensitive)
- E) Systemic manifestations in addition to corneal disease
Answer: C
Rationale: Kanski specifically states for GCD1: "Homozygous disease gives more severe features." This is an AD dystrophy where the TGFBI protein deposit accumulates proportionally. Homozygotes have two abnormal TGFBI alleles producing twice the amount of abnormal keratoepithelin, resulting in earlier onset and denser, more extensive opacities requiring earlier and more frequent keratoplasty. GCD1 heterozygotes typically need keratoplasty by the 5th decade; homozygotes may need it earlier. There are no systemic manifestations - this remains a pure corneal disease unlike Meretoja syndrome.
Q12. A 20-year-old patient with bilateral corneal opacities has histopathology showing deposits staining with both Masson trichrome (red) and Congo red (green birefringence under polarized light). What is the diagnosis?
- A) Granular corneal dystrophy type 1 (GCD1)
- B) Lattice corneal dystrophy type 1 (LCD1)
- C) Macular corneal dystrophy
- D) Avellino dystrophy (GCD2)
- E) Schnyder crystalline dystrophy
Answer: D
Rationale: Avellino dystrophy (GCD2) is the "combined granular-lattice dystrophy" - it deposits both hyaline (stains red with Masson trichrome) and amyloid (stains with Congo red and shows green birefringence). This dual histological staining pattern is pathognomonic for Avellino. Pure GCD1 stains only with Masson trichrome; pure LCD1 stains only with Congo red; Macular stains with Alcian blue. The clinical appearance of Avellino reflects this duality: stellate/annular granular-like deposits with deeper linear lattice-like opacities.
Q13. A 10-year-old child presents with frequent recurrent corneal erosions. Slit-lamp shows fine superficial stellate opacities in both corneas. The child's ethnicity is Korean. The most likely diagnosis and its TGFBI mutation are:
- A) Granular type 1; R555W
- B) Avellino dystrophy; R124H - higher prevalence in Korean/Japanese populations
- C) Reis-Bücklers; R555Q
- D) Lattice type 1; R124C
- E) Thiel-Behnke; R124S
Answer: B
Rationale: Avellino dystrophy (GCD2, R124H mutation) has a notably higher prevalence in Korean and Japanese populations compared to Western populations. Recognition of this ethnic predisposition is tested at fellowship level. Signs appear by end of first decade in heterozygotes (fine superficial stellate/annular opacities). The R124H mutation produces combined hyaline + amyloid deposits. This ethnic association is particularly important in the context of the high rate of refractive surgery (LASIK) in East Asian populations - preoperative TGFBI genetic screening is recommended in Korea.
Q14. Which statement about Lattice corneal dystrophy type 1 (LCD1) is INCORRECT?
- A) Amyloid deposits stain with Congo red and show apple-green birefringence under polarized light
- B) Recurrent erosions typically occur before stromal opacities are visible
- C) The lattice lines characteristically spare the periphery
- D) Corneal sensation is reduced
- E) The lattice lines typically extend from the periphery inward, sparing the central cornea
Answer: E
Rationale: Option E incorrectly describes LCD2 (Meretoja syndrome), NOT LCD1. In LCD1 (classic TGFBI type), the refractile dots and lattice lines start centrally and spread outward, sparing the periphery (as stated in option C, which is correct). In LCD2 (gelsolin, Meretoja), the sparse lattice lines spread centrally FROM the periphery - the opposite direction. This peripheral-to-central vs. central-to-peripheral spread is a key distinguishing feature between LCD1 and LCD2. All other options A-D correctly describe LCD1.
Q15. A 55-year-old Finnish patient presents with bilateral corneal opacities, bilateral peripheral facial nerve palsy (CN VII), protruding ears, mask-like facies, and dry, lax skin. What is the most likely corneal diagnosis, gene involved, and type of deposit?
- A) Lattice type 1; TGFBI; hyaline + amyloid
- B) Macular dystrophy; CHST6; GAGs
- C) Lattice type 2 (Meretoja syndrome); GSN; amyloid
- D) Granular type 1; TGFBI; hyaline
- E) Schnyder dystrophy; UBIAD1; cholesterol + phospholipid
Answer: C
Rationale: This is classic Meretoja syndrome (LCD2) - a systemic gelsolin amyloidosis with: corneal lattice dystrophy (sparse peripheral-to-central lattice lines), bilateral cranial nerve palsies (CN VII most characteristic → bilateral facial palsy), mask-like facies, protruding ears, and dry/lax skin (cutis laxa). The gene is GSN (gelsolin on chromosome 9q34). Amyloid deposits from mutant gelsolin (D187N mutation in most Finnish patients). The systemic features + Finnish/Scandinavian ethnicity + peripheral corneal lattice strongly identify this condition. It is the only corneal dystrophy that is truly a systemic disease.
Q16. A patient with macular corneal dystrophy (MCD) undergoes specular microscopy. Compared to a normal cornea, which finding would be most consistent with this condition?
- A) Normal endothelial cell density with regular hexagonal mosaic
- B) Beaten-metal appearance of endothelium with guttata
- C) Abnormal specular microscopy showing pleomorphism and polymegethism of endothelial cells
- D) Complete absence of endothelial cells
- E) Increased endothelial cell density (hypercellular)
Answer: C
Rationale: In macular corneal dystrophy, the glycosaminoglycan deposits affect not just keratocytes but also the corneal endothelium (unlike granular or lattice dystrophies which affect primarily keratocytes). Specular microscopy reveals abnormal endothelial cells with pleomorphism and polymegethism. This endothelial involvement explains why MCD can cause corneal thinning early and endothelial dysfunction later, and is part of why recurrence is more aggressive post-keratoplasty. This endothelial involvement makes MCD unique among the classic three stromal dystrophies.
SECTION 4: NON-TGFBI STROMAL DYSTROPHIES (Q17–19)
Q17. Schnyder corneal dystrophy (UBIAD1 gene) is described as having crystals in "half of patients." Which clinical feature is present in ALL patients regardless of whether crystals are visible?
- A) Anterior stromal cholesterol crystals
- B) Systemic dyslipidaemia
- C) Central corneal haze
- D) Dense arcus senilis
- E) Photophobia as the first symptom
Answer: C
Rationale: While crystals are present in only ~50% of patients (hence the recommendation to drop "crystalline" from the name), central corneal haze is the most consistent and early feature present in essentially all patients with Schnyder dystrophy. It represents diffuse phospholipid and cholesterol deposition throughout the anterior stroma. Dense arcus senilis (D) develops later and is also very common but is not universal in early disease. Systemic dyslipidaemia (B) is associated in some patients but not all - Wills Eye Manual recommends fasting serum lipid workup. The lack of crystals should NOT preclude the diagnosis.
Q18. Macular corneal dystrophy is caused by a defect in the CHST6 gene. What metabolic pathway is disrupted, and what is the downstream effect on corneal stromal architecture?
- A) Defective collagen hydroxylation → abnormal stromal collagen fibril spacing
- B) Defective keratan sulfate sulfotransferase → accumulation of unsulfated keratan sulfate intra- and extracellularly
- C) Defective gelsolin → abnormal actin cytoskeleton in keratocytes
- D) Defective lysosomal enzyme → mucopolysaccharide accumulation (as in MPS)
- E) Defective lipid metabolism → phospholipid and cholesterol deposits in stroma
Answer: B
Rationale: CHST6 encodes carbohydrate sulfotransferase 6, which sulfates corneal keratan sulfate. In MCD, this enzyme is defective, leading to accumulation of unsulfated (antigenic) keratan sulfate proteoglycans within keratocytes (intracellularly) and in the extracellular matrix. These abnormal glycosaminoglycans stain with Alcian blue and colloidal iron. The disruption of normal KS proteoglycan organization (lumican, keratocan, mimecan are the relevant corneal proteoglycans) destroys the precise collagen fibril spacing required for corneal transparency - hence the diffuse ground-glass opacification. Unlike MPS disorders (which have similar deposits), MCD is confined to the cornea with no systemic urine GAG abnormalities.
Q19. A 25-year-old with Schnyder corneal dystrophy complains of progressive glare and decreased vision, especially at night. Serum lipid profile shows elevated cholesterol. Regarding management, which statement is most accurate?
- A) Lipid-lowering therapy (statins) reliably reverses corneal deposits
- B) Statins may slow progression but do NOT reliably reverse existing corneal deposits; PTK is effective for anterior opacities; PKP/DALK for advanced disease
- C) Corneal transplantation is contraindicated due to extremely high recurrence risk
- D) This condition does not affect vision and only needs cosmetic management
- E) DMEK is the procedure of choice as the endothelium is predominantly affected
Answer: B
Rationale: Systemic lipid-lowering therapy (statins) has been studied in Schnyder dystrophy with inconsistent results - some small reports show stabilization but reliable reversal of established corneal crystalline deposits has not been demonstrated. The corneal management follows a stepwise approach: excimer laser PTK is effective for superficial anterior deposits and improving vision in early-to-moderate disease; PKP or DALK for advanced full-thickness involvement. Recurrence after keratoplasty occurs in Schnyder but is generally slower than in GCD or MCD. DMEK is incorrect as the endothelium is not primarily affected in Schnyder.
SECTION 5: ENDOTHELIAL DYSTROPHIES (Q20–26)
Q20. A 62-year-old woman complains of blurred vision that is worst on waking and improves by mid-morning. Slit-lamp shows subtle subepithelial grey changes and specular reflection reveals a "beaten-metal" endothelium. Pachymetry measures CCT 620 μm. She also needs cataract surgery. What is the most appropriate surgical approach?
- A) Cataract surgery alone; the morning improvement indicates adequate endothelial reserve
- B) Cataract surgery first, then monitor; perform DSAEK/DMEK only if decompensation occurs
- C) DMEK alone; the cataract will resolve with improved corneal transparency
- D) Combined phacoemulsification + IOL + DSAEK or DMEK (triple procedure)
- E) Topical NaCl 5% indefinitely; surgery is not indicated until visual acuity falls below 6/60
Answer: D
Rationale: This is Fuchs endothelial dystrophy with borderline CCT (620 μm is approaching but not yet at the 630-640 μm threshold). The beaten-metal endothelium indicates significant endothelial compromise. Cataract surgery alone risks permanent corneal decompensation because phacoemulsification stress further reduces endothelial cell count. When both cataract and Fuchs dystrophy need treatment, a combined "triple procedure" (phaco + IOL + DMEK or DSAEK) is appropriate in patients with pre-existing corneal edema or CCT approaching the threshold. Kanski explicitly states: "Cataract surgery may worsen the corneal status because of endothelial cell loss."
Q21. Regarding the pathophysiology of cornea guttata in Fuchs endothelial dystrophy, which statement is most accurate?
- A) Cornea guttata are excrescences of Bowman layer secreted by abnormal keratocytes
- B) Cornea guttata are irregular excrescences of Descemet membrane secreted by abnormal endothelial cells
- C) Cornea guttata represent lipid deposits within the endothelial cell cytoplasm
- D) Cornea guttata are subepithelial deposits of amyloid
- E) Cornea guttata are deposits of abnormal collagen in the stroma
Answer: B
Rationale: Cornea guttata are abnormal excrescences or "warts" on the posterior surface of Descemet membrane, secreted by genetically abnormal endothelial cells. The endothelial cells in Fuchs dystrophy secrete excess abnormal extracellular matrix (collagen type VIII is abnormal in early-onset variants due to COL8A2 mutations). These guttata are best seen on specular microscopy as dark spots disrupting the regular hexagonal endothelial mosaic, progressing to the classic "beaten metal" appearance. On PAS histology, they appear as rounded posterior projections of Descemet membrane. The guttata represent accelerated endothelial cell dysfunction and loss, ultimately causing corneal edema.
Q22. Why does the corneal edema in Fuchs dystrophy typically worsen in the morning and improve through the day?
- A) Increased IOP during sleep compresses the endothelium
- B) During sleep, the lids are closed, reducing evaporative dehydration of the cornea; overnight accumulation of fluid resolves with evaporation on eye opening
- C) Circadian variation in endothelial pump function is maximal at night
- D) Pupil dilation during sleep reduces aqueous circulation
- E) Nocturnal reduction in tear pH activates corneal edema
Answer: B
Rationale: The classic morning worsening of vision in Fuchs dystrophy occurs because during sleep, the closed lids eliminate evaporation from the corneal surface. This allows fluid that leaks through the dysfunctional endothelium to accumulate in the stroma and epithelium. On waking, evaporation from the open eye surface acts as an additional dehydrating force and gradually clears the edema over the first few hours. This is the physiological basis for the conservative treatment recommendation of using a hair dryer at arm's length to enhance evaporation and for prescribing hypertonic NaCl 5% drops (to draw water osmotically from the cornea).
Q23. In Posterior Polymorphous Corneal Dystrophy (PPCD), the pathological hallmark is endothelial cell metaplasia. What cellular behaviour change occurs and what complications does it cause?
- A) Endothelial cells lose pump function only, causing edema without structural change
- B) Endothelial cells acquire epithelial-like behaviour: stratification, microvilli, desmosomes → can migrate onto iris/angle causing glaucoma and iridocorneal adhesions
- C) Endothelial cells become fibroblastic and produce excess Descemet membrane collagen
- D) Endothelial cells undergo apoptosis and are replaced by stromal keratocytes
- E) Endothelial cells become melanocyte-like and produce pigment deposits on angle structures
Answer: B
Rationale: PPCD is caused by metaplastic endothelial cells that acquire epithelial-like properties: they stratify (multiple cell layers instead of single monolayer), form microvilli, express epithelial markers (cytokeratins), and form intercellular junctions (desmosomes). Because these cells proliferate and migrate anteriorly, they can extend as a membrane over the trabecular meshwork and iris → causing peripheral anterior synechiae (PAS), corectopia (displaced pupil), and secondary glaucoma. This explains why PPCD is associated with iris abnormalities and elevated IOP. The association with Alport syndrome (COL4A3/4/5 mutations) is via shared collagen IV abnormalities.
Q24. CHED1 vs. CHED2: A newborn is found to have bilateral diffuse corneal clouding with a ground-glass blue-grey appearance at birth, associated with horizontal nystagmus. There is no photophobia or epiphora. Which type is this most likely, and what is the key gene?
- A) CHED1; COL8A2 gene; AD inheritance
- B) CHED2; SLC4A11 gene; AR inheritance
- C) CHED1; TCF4 gene; AD inheritance
- D) CHED2; ZEB1 gene; AR inheritance
- E) PPCD3; ZEB1 gene; AD inheritance
Answer: B
Rationale: The clinical scenario describes CHED2: neonatal bilateral corneal clouding (present at birth), nystagmus (more common in CHED2 than CHED1), and the absence of photophobia/watering (which are characteristic of CHED1 but NOT CHED2). CHED2 is AR, caused by SLC4A11 mutations. CHED2 is more common and more severe than CHED1. CHED2 is occasionally associated with late-onset sensorineural deafness = Harboyan syndrome. Visual acuity in CHED can surprisingly surpass what is expected from the corneal appearance. Early keratoplasty is recommended to prevent amblyopia.
Q25. A patient with Fuchs endothelial dystrophy is being evaluated for corneal transplantation. Comparing DMEK to DSAEK, which statement most accurately represents current evidence?
- A) DSAEK gives better visual outcomes due to thicker graft supporting the stroma
- B) DMEK provides faster visual recovery and better final visual acuity (often 6/6 or better) but has a higher technical complexity and rebubbling rate
- C) DMEK and DSAEK give identical visual outcomes; choice depends only on surgeon preference
- D) PKP remains superior to both lamellar techniques for Fuchs dystrophy
- E) DMEK is contraindicated in patients with deep-set eyes or small palpebral apertures
Answer: B
Rationale: DMEK (transplant of Descemet membrane + endothelium only, ~10-15 μm thick) gives superior visual outcomes to DSAEK (transplant includes posterior stroma, ~100-150 μm thick) because: (1) no interface haze from retained donor stroma, (2) faster visual recovery, (3) final BCVA frequently 6/6 or better (vs. 6/9 average for DSAEK). However, DMEK has a steeper learning curve and higher rebubbling rate (~30-40% vs. ~5% for DSAEK). DSAEK remains preferred in some situations (e.g., concurrent glaucoma drainage device, challenging anatomy). Both are superior to PKP for Fuchs due to faster recovery and lower rejection risk.
Q26. In a patient with Fuchs dystrophy, the Rho-kinase (ROCK) inhibitor (e.g., ripasudil/netarsudil) combined with prior transcorneal endothelial cryotherapy is described as a promising treatment. What is the mechanism of action?
- A) Inhibits aqueous production, reducing corneal hydration pressure
- B) Inhibits the Rho/ROCK pathway, promoting endothelial cell proliferation and migration, potentially regenerating functional endothelium
- C) Directly lyses abnormal Descemet membrane guttata
- D) Increases corneal endothelial pump expression via cAMP pathway
- E) Promotes epithelial stem cell migration from limbus to replace endothelial cells
Answer: B
Rationale: Corneal endothelial cells are normally arrested in G1 phase and do not proliferate in vivo. The Rho/ROCK pathway maintains this G1 arrest. ROCK inhibitors (ripasudil, Y-27632, netarsudil) block this pathway, enabling endothelial cells to proliferate, spread, and migrate - effectively promoting regeneration of functional endothelium. Combined with transcorneal endothelial cryotherapy (to selectively destroy the abnormal guttata-bearing endothelial cells), ROCK inhibitors allow the surviving peripheral endothelial cells to repopulate the cornea. This approach could potentially avoid corneal transplantation in early-to-moderate Fuchs. This is an actively developing therapeutic area and is specifically mentioned in Kanski 10e.
SECTION 6: CLINICAL SCENARIOS, HISTOLOGY & HIGH-YIELD FACTS (Q27–30)
Q27. A 16-year-old presents with bilateral painless slowly progressive corneal opacification. Fundoscopy is normal. The corneas appear thinner than average on pachymetry. Slit-lamp shows diffuse grey-white cloudy opacities extending from limbus to limbus, denser anteriorly in the centre and more posteriorly toward the periphery. The intervening stroma is also hazy (no clear zone). Alcian blue staining of a biopsy shows both intra- and extracellular positive deposits. The most likely diagnosis and expected recurrence pattern after PKP are:
- A) Lattice type 1; recurrence within 5 years
- B) Granular type 1; recurrence by 5th decade in the graft
- C) Macular corneal dystrophy; recurrence can occur many years after keratoplasty
- D) Schnyder dystrophy; recurrence is very rare
- E) EBMD; no recurrence as it is epithelial only
Answer: C
Rationale: The clinical picture is classic MCD: limbus-to-limbus cloudy opacities with no clear intervening stroma, corneal thinning (early and characteristic), diffuse full-thickness involvement, Alcian blue positive (GAGs intra- and extracellularly). Regarding post-keratoplasty recurrence: all three classic stromal dystrophies recur in grafts, but MCD can recur many years post-PKP. The genetic defect in keratocytes (CHST6) persists as host keratocytes repopulate the graft. Similarly, GCD1 and LCD1 recur within ~5 years of PTK or keratoplasty. Wills Eye Manual states MCD "may recur many years after corneal transplantation."
Q28. You are evaluating a 40-year-old before refractive surgery. Slit-lamp shows subtle central anterior stromal haze. Topography shows irregular astigmatism. Review of the family history reveals the patient's father had "corneal problems requiring transplant." Specular microscopy is normal. Which pre-operative screening test would most change your surgical plan?
- A) Corneal OCT (AS-OCT) to measure epithelial thickness map
- B) TGFBI genetic mutation screening (R124H, R555W, R124C, R555Q)
- C) Confocal microscopy for Meesmann cysts
- D) Serum keratan sulfate level
- E) Impression cytology for epithelial goblet cells
Answer: B
Rationale: The scenario raises concern for a TGFBI-related dystrophy (positive family history + subtle anterior stromal changes). TGFBI genetic screening is the most critical test because identification of specific mutations (especially R124H = Avellino/GCD2) would absolutely contraindicate refractive surgery. LASIK in an Avellino patient causes catastrophic worsening. Serum KS levels are used for macular dystrophy (not relevant here). AS-OCT and confocal microscopy cannot definitively identify TGFBI mutations. In Korea and Japan, population-based TGFBI screening before refractive surgery has been formally recommended because of the high Avellino carrier rate.
Q29. A histopathology slide from an excised corneal button shows deposits that stain with Masson trichrome (bright red/magenta), with Congo red (positive under polarized light showing green birefringence), AND with Alcian blue. What diagnosis should be considered?
- A) Pure granular dystrophy type 1
- B) Pure lattice dystrophy type 1
- C) Advanced macular dystrophy with secondary amyloid deposits
- D) Avellino (GCD2) - but triple staining pattern does NOT occur in Avellino alone
- E) There is no single dystrophy that gives all three positive stains; this likely represents combined/advanced disease or misdiagnosis
Answer: E
Rationale: This is a high-level discriminator. The three classic staining patterns are:
- Masson trichrome (red) = hyaline → GCD1, GCD2
- Congo red (green birefringence) = amyloid → LCD1, GCD2
- Alcian blue = GAGs/keratan sulfate → Macular dystrophy
No single dystrophy produces all three. GCD2 (Avellino) produces the first two (hyaline + amyloid = Masson + Congo red). In late-stage macular dystrophy, secondary amyloid deposits may accumulate but primary staining is Alcian blue. A triple-positive pattern would suggest combined pathology or misclassification - this scenario is designed to test whether candidates understand that each dystrophy has a specific deposit type and stain. Fellowship examiners may present mixed/atypical histology to test precise knowledge of staining specificity.
Q30. A 45-year-old patient with bilateral corneal opacities since childhood is found to have elevated serum cholesterol and triglycerides. Slit-lamp shows central corneal haze with a notably dense arcus senilis (for their age). Crystals are NOT visible on slit-lamp. The most likely diagnosis and the correct gene are:
- A) Macular dystrophy; CHST6
- B) Schnyder corneal dystrophy; UBIAD1 — crystals absent but central haze present; dyslipidaemia association
- C) Bietti crystalline dystrophy; CYP4V2
- D) Lattice type 1; TGFBI — lipid component is secondary
- E) Tangier disease; ABCA1 — corneal lipid deposits
Answer: B
Rationale: The absence of crystals does NOT exclude Schnyder dystrophy - crystals are present in only ~50% of patients. The defining features here are: bilateral central corneal haze (present in ALL Schnyder patients), dense arcus senilis at a young age, associated dyslipidaemia (phospholipid/cholesterol metabolism disorder), and UBIAD1 gene mutation. Wills Eye Manual explicitly recommends fasting lipid workup (serum cholesterol + triglycerides) in all Schnyder patients. Bietti crystalline dystrophy (CYP4V2) produces peripheral retinal and corneal crystals with progressive retinopathy. Tangier disease (ABCA1) causes orange tonsils and corneal stromal clouding from cholesterol deposits but is a systemic HDL deficiency syndrome. The clinical scenario most precisely fits Schnyder dystrophy.
Summary Answer Key
| Q | Topic | Answer |
|---|---|---|
| 1 | IC3D classification - LCD2 grouping error | E |
| 2 | Avellino + refractive surgery contraindication | C |
| 3 | Inheritance patterns | B |
| 4 | TGFBI codon R555W mutation | C |
| 5 | Gene-dystrophy matching | B |
| 6 | EBMD clinical scenario | B |
| 7 | Meesmann gene product + distinguishing feature | B |
| 8 | Reis-Bücklers vs Thiel-Behnke distinction | C |
| 9 | RB dystrophy prognosis/treatment | C |
| 10 | GCD1 triad | C |
| 11 | GCD1 homozygous severity | C |
| 12 | Dual Masson+Congo red staining | D |
| 13 | Avellino + Korean ethnicity + R124H | B |
| 14 | LCD1 incorrect statement | E |
| 15 | Meretoja syndrome systemic features | C |
| 16 | MCD endothelial involvement | C |
| 17 | Schnyder: universal feature | C |
| 18 | MCD metabolic pathway | B |
| 19 | Schnyder management | B |
| 20 | Fuchs + cataract - triple procedure | D |
| 21 | Cornea guttata pathophysiology | B |
| 22 | Morning worsening mechanism | B |
| 23 | PPCD metaplasia mechanism | B |
| 24 | CHED2 neonatal presentation | B |
| 25 | DMEK vs DSAEK | B |
| 26 | ROCK inhibitor mechanism | B |
| 27 | MCD clinical scenario + recurrence | C |
| 28 | Pre-refractive surgery screening | B |
| 29 | Triple histochemical staining | E |
| 30 | Schnyder without crystals | B |
Sources: Kanski's Clinical Ophthalmology 10e (pp.265-276); Wills Eye Manual 8e (Ch. 4.25-4.26); Goldman-Cecil Medicine
As an ophthalmologist preparing for post doctoral fellowship test my knowledge by asking advance level mcqs (30) on general ophthalmology
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I now have rich, verified source material from Kanski's 10e and Wills Eye Manual 8e covering glaucoma, retina, cataract, cornea, uveitis, and more. I'll now craft 30 rigorous fellowship-level MCQs spanning all major subspecialties of general ophthalmology.
Advanced General Ophthalmology — 30 Fellowship MCQs
Source: Kanski's Clinical Ophthalmology 10e | Wills Eye Manual 8e | Goldman-Cecil Medicine
SECTION 1: GLAUCOMA (Q1–7)
Q1. The LiGHT trial (Laser in Glaucoma and Ocular Hypertension) fundamentally changed the management of POAG. What was its primary conclusion and what laser was used?
- A) Argon laser trabeculoplasty (ALT) is superior to SLT as first-line therapy
- B) Selective laser trabeculoplasty (SLT) at 532 nm should be recommended as first-line treatment in ocular hypertension and POAG; patients were more likely to be drop-free and at target pressure at 3 years
- C) SLT is equivalent to medical therapy only when used as adjunctive treatment
- D) Micropulse laser trabeculoplasty is superior to SLT for IOP reduction
- E) SLT confers neuroprotective benefit independent of IOP lowering
Answer: B
Rationale: The LiGHT trial demonstrated that SLT as first-line therapy (vs. drops first) resulted in fewer patients requiring trabeculectomy or phacoemulsification at 6 years, and ~80% of SLT-first patients were drop-free and at target pressure at 3 years. SLT uses a 532 nm frequency-doubled Q-switched Nd:YAG laser to selectively target melanin-containing TM cells, sparing non-pigmented structures (no thermal damage). IOP reductions of 10-40% can be expected; ~25% reduction is common. Because there is no tissue destruction, SLT can be repeated even if initial treatment was unsuccessful - a key advantage over ALT. Kanski 10e specifically states SLT is "recommended as first-line treatment in patients with ocular hypertension and POAG" based on the LiGHT trial.
Q2. A 60-year-old woman presents with acute-onset severe headache, nausea, periorbital pain, and blurred vision in her right eye. IOP right eye is 58 mmHg. The cornea is steamy, the pupil is mid-dilated and non-reactive, and the anterior chamber is shallow. She reports a similar milder episode 3 months ago that resolved spontaneously. The untreated fellow eye carries what risk of an acute attack?
- A) <5% lifetime risk
- B) 10-20% over 5 years
- C) 40-80% over 5 to 10 years
- D) Only at risk if similarly precipitated by mydriasis
- E) No risk; acute angle closure is almost always unilateral
Answer: C
Rationale: The Wills Eye Manual explicitly states: "An untreated fellow eye has a 40-80% chance of acute angle closure in 5 to 10 years." This is the evidence base for prophylactic laser peripheral iridotomy (LPI) of the fellow eye. Importantly, if the presenting (affected) eye is too inflamed for immediate LPI, the recommendation is to perform laser PI of the fellow eye first. The scenario describes classic acute primary angle closure (APAC) with the hallmarks: shallow AC, mid-dilated non-reactive pupil (iris sits against lens blocking aqueous flow through pupil = pupillary block), IOP spike, steamy cornea, and prodromal subacute attacks.
Q3. A 70-year-old hyperopic patient presents with acute angle closure. IOP is controlled medically. The cornea clears. Which management decision regarding the fellow eye is INCORRECT?
- A) Laser peripheral iridotomy to the fellow eye should be performed as soon as the affected eye is quiet
- B) Laser PI of the fellow eye should be performed FIRST if the affected eye is too inflamed
- C) If IOP does not decrease after maximal medical therapy, laser PI should be attempted even with some corneal haze
- D) Pilocarpine 2% every 15 minutes is currently the first-line definitive treatment
- E) Phacomorphic glaucoma co-existing with pupillary block requires lens extraction once IOP is controlled
Answer: D
Rationale: Pilocarpine has traditionally been used in APAC but has "fallen out of favour by some physicians" (Wills Eye Manual) due to: headache, accommodative spasm, increased risk of uveitis and retinal detachment, and paradoxically potential for miosis-induced angle closure (by increasing relative pupillary block in some configurations). The definitive treatment is YAG laser PI or surgical iridectomy performed once the cornea clears and AC is quiet (typically 1-5 days post-attack). Options A, B, C, and E are all correct management principles.
Q4. Topiramate-induced bilateral angle closure is a distinct entity from primary angle closure. Which management approach is SPECIFICALLY DIFFERENT from standard primary angle closure treatment?
- A) Peripheral iridotomy and miotics are the first-line treatment
- B) Immediate discontinuation of topiramate + cycloplegia (atropine) to rotate ciliary body posteriorly; CAIs (acetazolamide) are contraindicated; PI and miotics are NOT indicated
- C) Anti-VEGF injection reduces the choroidal effusion driving the mechanism
- D) Beta-blocker eye drops are contraindicated due to sulfonamide cross-reactivity
- E) IV mannitol is contraindicated as it worsens the supraciliary effusion
Answer: B
Rationale: Topiramate (and other sulfonamide derivatives) cause a secondary angle closure via uveal effusion/ciliary body rotation (idiosyncratic swelling of the ciliary body pushing the lens-iris diaphragm anteriorly) - NOT pupillary block. Therefore: (1) PI and miotics are NOT indicated and may worsen the condition; (2) the drug must be immediately discontinued; (3) cycloplegia (atropine) rotates the ciliary body posteriorly, deepening the AC; (4) carbonic anhydrase inhibitors (CAIs) are contraindicated in sulfonamide-induced angle closure due to cross-reactivity risk; (5) IV hyperosmotic agents and IV steroids may be needed for refractory cases. This is a critical clinical distinction tested at fellowship level.
Q5. Regarding the mechanism of glaucoma in Sturge-Weber syndrome, which statement is most accurate?
- A) Only pupillary block mechanism is responsible for IOP elevation
- B) In infants: trabeculodysgenesis; in older patients: raised episcleral venous pressure from episcleral haemangioma arteriovenous communication
- C) Elevated IOP results exclusively from neovascular angle closure
- D) Choroidal haemangioma compresses the trabecular meshwork directly
- E) Mechanism is identical at all ages and stages of the condition
Answer: B
Rationale: Kanski 10e describes a biphasic mechanism in Sturge-Weber glaucoma: (1) In infants (~60% of cases with glaucoma present before age 2 and may develop buphthalmos): trabeculodysgenesis is the predominant mechanism (similar to primary congenital glaucoma); (2) In older patients: raised episcleral venous pressure associated with arteriovenous communication in an episcleral haemangioma is the predominant mechanism. Surgical risk in Sturge-Weber is the significant risk of choroidal effusion and suprachoroidal haemorrhage (due to the diffuse choroidal haemangioma) with any filtration surgery. Treatment in early-onset cases: combined trabeculotomy-trabeculectomy.
Q6. Pseudoexfoliation (exfoliation) syndrome is the most common identifiable cause of open-angle glaucoma worldwide. Which ocular finding is NOT typically associated with pseudoexfoliation syndrome?
- A) White flaky material on the anterior lens capsule with a central disc, clear zone, and peripheral granular zone
- B) Weakened zonules predisposing to lens subluxation during cataract surgery
- C) Poorly dilating pupil due to sphincter involvement
- D) Pigment dispersion on the corneal endothelium in a Krukenberg spindle (vertical) pattern
- E) Increased intraocular pressure more difficult to control compared to POAG
Answer: D
Rationale: A Krukenberg spindle (vertical, fusiform pigment deposit on central corneal endothelium) is pathognomonic of Pigment Dispersion Syndrome (PDS), NOT pseudoexfoliation syndrome. In PDS, iris pigment is shed due to iridozonular friction and deposits on the corneal endothelium in the vertical distribution of aqueous convection currents. In pseudoexfoliation syndrome, pigment is deposited but typically on the anterior lens surface, ciliary processes, zonules, and trabecular meshwork - not in the Krukenberg spindle pattern. Options A, B, C, and E are all genuine features of pseudoexfoliation syndrome.
Q7. A 65-year-old with advanced POAG undergoes trabeculectomy with mitomycin C. Six months later, the bleb is overhanging, avascular, thin-walled, and the eye is hypotonous (IOP 4 mmHg). The patient reports blurred vision. What is the most likely diagnosis and its risk?
- A) Early bleb failure with fibrosis; requires 5-FU needling
- B) Tenon's cyst (encapsulated bleb); requires surgical revision
- C) Bleb-related endophthalmitis; requires emergency vitreous tap
- D) Overfiltration with hypotony maculopathy; thin avascular bleb is at risk of bleb leak and bleb-related endophthalmitis
- E) Normal post-trabeculectomy appearance; no intervention needed
Answer: D
Rationale: This is a classic hypotony maculopathy with a thin, avascular, overhanging bleb - the consequence of MMC-augmented trabeculectomy producing excessive filtration. Hypotony (IOP <6-8 mmHg) causes choroidal engorgement and macular folding → blurred vision. The thin avascular bleb (also called "champagne bubble" bleb) is the most dangerous long-term complication: it carries a lifetime risk of bleb-related endophthalmitis (Streptococcus, Haemophilus influenzae most common pathogens), which can occur years to decades after surgery. Treatment of hypotony: autologous blood injection, bleb revision, or compression sutures. Patients must be educated about signs of infection.
SECTION 2: RETINA (Q8–14)
Q8. A 45-year-old high myope reports a sudden onset of multiple floaters and flashing lights. Fundoscopy reveals a horseshoe tear at the 11 o'clock position superiortemporally with a small amount of subretinal fluid. Visual field is full. What is the single most important immediate action?
- A) Observe for 48 hours; most horseshoe tears do not progress to detachment
- B) Urgent pneumatic retinopexy
- C) Urgent laser retinopexy (photocoagulation) or cryotherapy to the tear to create a chorioretinal adhesion barrier
- D) Vitrectomy to relieve vitreoretinal traction at the tear
- E) Anti-VEGF injection to reduce neovascular risk at the tear site
Answer: C
Rationale: A symptomatic horseshoe tear (flashes + floaters + tear with vitreoretinal traction + early subretinal fluid) is an urgent condition requiring same-day or next-day treatment with laser photocoagulation (2-3 rows of burns surrounding the tear) or cryotherapy to create a chorioretinal adhesion that prevents progression to full rhegmatogenous RD. An untreated symptomatic horseshoe tear has a high risk of progression to RD. Kanski 10e emphasizes that over 40% of RDs occur in myopic eyes, and horseshoe tears with traction and SRF must be treated urgently. Observation (A) is only appropriate for asymptomatic atrophic round holes in non-myopic eyes with no subretinal fluid.
Q9. Lincoff's rules help predict the location of the primary break in a rhegmatogenous RD. A patient has a bullous inferior retinal detachment. According to Lincoff's rules, where is the primary break most likely located?
- A) Inferotemporally at 6 o'clock
- B) At the inferonasal periphery
- C) Above the horizontal meridian (superior quadrant)
- D) At 3 or 9 o'clock (horizontal meridian)
- E) Within the macula as a macular hole
Answer: C
Rationale: This is Lincoff's rule 3: "In a bullous inferior RD, the primary break usually lies above the horizontal meridian." The reasoning is that a superior break allows rapid accumulation of subretinal fluid that fills the inferior fundus in a bullous manner under gravity. Other Lincoff rules: (1) Shallow inferior RD with fluid slightly higher on the temporal side = break inferotemporally on that side; (2) Inferior RD with equal levels = break at 6 o'clock; (4) Upper nasal break = SRF revolves around disc then rises on temporal side; (5) Subtotal RD with superior wedge attached = break in periphery nearest its highest border; (6) SRF crosses vertical midline above = break near 12 o'clock.
Q10. The ETDRS and subsequent anti-VEGF trials transformed diabetic macular oedema (DMO) management. Regarding the current evidence for treatment of centre-involving DMO, which statement is most accurate?
- A) Laser photocoagulation (ETDRS focal/grid) remains the gold standard treatment
- B) Anti-VEGF is now first-line treatment for centre-involving DMO with visual acuity impairment, with laser reserved for non-centre-involving lesions and macular ischaemia
- C) Intravitreal steroids (triamcinolone, dexamethasone implant) are preferred over anti-VEGF for centre-involving DMO regardless of lens status
- D) Tight glycaemic control alone is sufficient to reverse established centre-involving DMO
- E) PDT with verteporfin is the preferred treatment for DMO in pseudophakic eyes
Answer: B
Rationale: Following the ETDRS trial (which established modified focal/grid laser), the DRCR.net Protocol T (and subsequent real-world evidence) demonstrated the superiority of anti-VEGF (ranibizumab, aflibercept, bevacizumab) over laser for centre-involving DMO with VA impairment. Specifically, aflibercept showed superiority over bevacizumab and ranibizumab when baseline VA was ≤20/50. The current standard is: anti-VEGF is first-line for centre-involving DMO affecting VA; laser (modified ETDRS) is reserved for non-centre-involving DMO, residual hard exudates threatening the fovea, or in phakic patients as adjunct to reduce injection frequency. Intravitreal steroids are useful in pseudophakic eyes, treatment-naïve patients, or those with poor response to anti-VEGF.
Q11. A 55-year-old type 2 diabetic has proliferative diabetic retinopathy (PDR) with high-risk characteristics (HRC). According to the Diabetic Retinopathy Study (DRS), which finding defines a high-risk characteristic?
- A) Microaneurysms and dot haemorrhages in all four quadrants
- B) New vessels on the disc (NVD) ≥ one-quarter to one-third disc area, OR NVD with vitreous/preretinal haemorrhage, OR NVE with vitreous/preretinal haemorrhage
- C) Clinically significant macular oedema (CSME) threatening the fovea
- D) Cotton wool spots in more than two quadrants
- E) Intraretinal microvascular abnormalities (IRMA) in ≥2 quadrants
Answer: B
Rationale: The DRS high-risk characteristics (HRC) for severe visual loss in PDR are:
- NVD ≥ 1/4-1/3 disc area (even without haemorrhage)
- Any NVD with vitreous or preretinal haemorrhage
- NVE with vitreous or preretinal haemorrhage (NVE alone is not HRC)
Presence of any ONE of these triples the risk of severe visual loss and mandates panretinal photocoagulation (PRP). The DRS showed PRP reduced the risk of severe visual loss (VA ≤5/200) by >50% in eyes with HRC. CSME (option C) is the ETDRS criteria for macular oedema requiring focal laser. Options D and E describe pre-proliferative features (severe NPDR/4-2-1 rule) rather than proliferative HRC.
Q12. A 32-year-old woman on oral contraceptives presents with sudden painless central vision loss in the right eye. Fundoscopy shows a cherry-red spot at the fovea with surrounding retinal whitening. The optic disc appears normal. What is the most likely diagnosis and the immediate management priority?
- A) Branch retinal artery occlusion; observe and arrange carotid Doppler
- B) Central retinal artery occlusion (CRAO); immediate ocular massage, IOP-lowering, and urgent systemic evaluation for embolic source and stroke risk
- C) Optic neuritis; IV methylprednisolone
- D) Non-arteritic AION; aspirin and refer
- E) Commotio retinae; observe
Answer: B
Rationale: Cherry-red spot at the fovea with surrounding pale/white retina = CRAO (central retinal artery occlusion). The fovea appears red because the thin foveola allows visualization of the underlying choroidal circulation, while the surrounding thicker retina (supplied by CRA) becomes white from ischaemic oedema. Immediate management (within 4-6 hour window): ocular massage (dislodge embolus), anterior chamber paracentesis (reduce IOP acutely), IOP-lowering medications, rebreathing into paper bag (CO2 vasodilation). However, the evidence for visual recovery from acute interventions remains limited. More critically: CRAO is a stroke equivalent (15-25% 30-day stroke risk); urgent carotid imaging, echocardiography, cardiac monitoring, and neurology referral are mandatory. Oral contraceptive use is a relevant thrombotic risk factor.
Q13. The CATT (Comparison of AMD Treatments Trial) study compared ranibizumab and bevacizumab for neovascular AMD. What was the primary conclusion?
- A) Ranibizumab was significantly superior to bevacizumab at 2 years
- B) Monthly dosing was clearly superior to PRN dosing for all agents at 2 years
- C) Bevacizumab demonstrated non-inferiority to ranibizumab at 1 year; both agents showed similar visual outcomes though bevacizumab had a slightly higher rate of serious systemic adverse events
- D) Aflibercept was superior to both ranibizumab and bevacizumab
- E) Thermal laser photocoagulation was superior to all anti-VEGF agents for classic CNV
Answer: C
Rationale: The CATT trial (NEJM 2011) established that bevacizumab is non-inferior to ranibizumab at 1 year for visual acuity outcomes in neovascular AMD. The trial also showed that monthly dosing achieved slightly better anatomic (fluid dryness) but similar functional outcomes to PRN (as-needed) dosing. Importantly, bevacizumab at ~$50/injection vs. ranibizumab at ~$2000/injection represents enormous healthcare cost savings. The trial noted a statistically higher rate of serious systemic adverse events (predominantly GI and vascular) with bevacizumab, though the absolute risk difference was small and subsequent analyses debated its significance. Aflibercept (option D) was not part of CATT - its evidence base comes from the VIEW trials.
Q14. In the management of rhegmatogenous retinal detachment (RRD), which factor most strongly favours pneumatic retinopexy over scleral buckling or vitrectomy?
- A) Presence of proliferative vitreoretinopathy (PVR) grade C
- B) Multiple breaks scattered in more than 2 clock hours
- C) Single break, superior, ≤1 clock hour in size, phakic eye, no significant PVR
- D) Inferior RD with a break at 6 o'clock
- E) Aphakic RD with undetectable break
Answer: C
Rationale: Pneumatic retinopexy (intravitreal gas injection + laser/cryo to break) is ideal for: single break, superior location (above 8-4 o'clock), ≤1 clock hour size, phakic, no significant PVR, no inferior breaks, compliant patient who can maintain posturing. It is the least invasive of the three RD repair techniques and has success rates comparable to scleral buckling for suitable cases. It is contraindicated for: inferior breaks (gas can't reach), multiple scattered breaks >2 clock hours, PVR (C and above), significant media opacity, and inability to posture. Options A (PVR), B (multiple scattered breaks), D (inferior break), and E (aphakic with undetected break) all favour vitrectomy or scleral buckling.
SECTION 3: CATARACT & ANTERIOR SEGMENT (Q15–20)
Q15. During routine phacoemulsification, posterior capsule rupture (PCR) occurs during nucleus removal with vitreous prolapse into the anterior chamber. Which is the MOST APPROPRIATE immediate next step?
- A) Continue phacoemulsification to clear the remaining nuclear fragments quickly
- B) Immediately inject viscoelastic to tamponade, stop phaco, call for anterior vitrectomy setup, and manage the vitreous prolapse before continuing with lens implantation
- C) Convert to ECCE immediately without any additional steps
- D) Inject intravitreal triamcinolone to reduce inflammation
- E) Abandon the surgery and reschedule after 6 weeks
Answer: B
Rationale: PCR with vitreous loss is a serious complication requiring a structured response: (1) Stop phacoemulsification immediately - continuing risks nuclear fragments dropping into the vitreous; (2) Inject OVD (viscoelastic) to pressurize the AC, tamponade the vitreous, and protect the endothelium; (3) Perform anterior vitrectomy to clear vitreous from the AC (leaving vitreous in the AC leads to cystoid macular oedema, raised IOP, corneal decompensation); (4) Assess whether a sulcus IOL (3-piece) can be safely implanted with intact anterior capsule rim for support; (5) If insufficient capsular support: anterior chamber IOL or iris-fixated IOL. Continuing phaco through vitreous (A) risks nucleus drop and retinal damage.
Q16. A patient with diabetes is scheduled for cataract surgery. Preoperative central corneal thickness (CCT) is 655 μm, and specular microscopy shows polymegethism and pleomorphism of the endothelium without frank guttata. What is the most appropriate counselling regarding surgical risk?
- A) Surgery is absolutely contraindicated; wait for spontaneous improvement
- B) CCT 655 μm exceeds the threshold of 630-640 μm; there is a significant risk of persistent corneal oedema post-operatively; consider combined cataract + DMEK if Fuchs is confirmed, or proceed with careful phaco minimizing endothelial stress
- C) Diabetes is the only risk factor; standard surgery proceeds without modification
- D) Only CCT >700 μm poses a clinically meaningful risk
- E) Posterior chamber phacoemulsification carries no higher endothelial risk than ECCE in this scenario
Answer: B
Rationale: Kanski 10e explicitly states: "Persistent corneal oedema may follow cataract surgery in a patient with Fuchs endothelial dystrophy, particularly if the preoperative central corneal thickness is more than 630-640 μm." At CCT 655 μm, this patient is above this threshold. The pleomorphism/polymegethism on specular microscopy suggests compromised endothelial reserve consistent with early Fuchs or other endotheliopathy. Options include: minimize phaco energy (low-energy techniques, dispersive OVD), consider combined phaco + DMEK (triple procedure) if clinical Fuchs is confirmed, counsel the patient about potential need for corneal transplantation post-operatively. Option C is incorrect - Fuchs dystrophy risk supersedes diabetes in this context.
Q17. A 6-week-old infant is found to have a unilateral dense posterior subcapsular and nuclear cataract at birth. Both eyes show normal anterior segments. What is the management priority and timing?
- A) Observe until age 2 then operate; early surgery carries unacceptable risks
- B) Urgent cataract surgery within the first 6-8 weeks of life, followed by optical rehabilitation (aphakic contact lens or IOL) and aggressive amblyopia treatment to maximize visual development during the critical period
- C) Glasses prescription first; surgery only if VA does not improve
- D) Surgery at age 1 year followed by standard spectacle correction
- E) Anti-VEGF injection to the vitreous to prevent retinal complications
Answer: B
Rationale: A dense unilateral congenital cataract is a deprivational amblyopia emergency. The critical period for visual development (Hubel and Wiesel) extends primarily from birth to 6-8 years, with the most sensitive period in the first 3-4 months. Deprivation of visual input during this period causes irreversible cortical visual suppression. Current guidelines recommend: (1) Surgery within the first 6-10 weeks to restore optical clarity; (2) Optical rehabilitation: infant aphakic contact lenses are preferred in the first years; IOL implantation is now used in infants >1 month by many surgeons though aphakia with delayed IOL implantation (age 4-5 years) is also practised; (3) Patching of the fellow eye (1-4 hours/day depending on age) to force use of the amblyopic eye throughout the treatment period.
Q18. A 70-year-old patient undergoes uneventful phacoemulsification and IOL implantation. Three months later, they develop progressive blurring. Retroillumination shows a "wrinkled cellophane" appearance at the posterior capsule. Nd:YAG laser capsulotomy is planned. What is the most common serious complication of Nd:YAG capsulotomy and how is it minimized?
- A) Optic nerve damage; use minimum energy and peripheral capsulotomy
- B) Elevated IOP spike (transient but occasionally sustained); pre-treat with apraclonidine or brimonidine and monitor IOP post-procedure; IOL pitting; risk of cystoid macular oedema; rare retinal detachment (risk 1-4%, especially in myopes)
- C) Corneal decompensation from endothelial damage; protect with OVD
- D) Acute uveitis; pre-treat with topical steroids for 1 week before procedure
- E) IOL dislocation into the vitreous; use minimum energy and gentle technique
Answer: B
Rationale: Posterior capsule opacification (PCO) is the most common late complication of cataract surgery (occurs in up to 40% within 2 years without modern square-edged IOLs). Nd:YAG capsulotomy complications include: (1) IOP spike - most common (can be substantial, pre-treated with apraclonidine 1% or brimonidine); (2) IOL pitting (cosmetically significant with some IOL materials); (3) Cystoid macular oedema (CMO); (4) Rhegmatogenous retinal detachment - this is the most serious structural complication (1-4% lifetime risk, higher in myopes - up to 8x increased risk); (5) Anterior uveitis (less common). The RD risk is particularly important to counsel myopic patients about before proceeding.
Q19. In assessing a patient for phacoemulsification, which biometric formula is most appropriate for an axial length of 30.5 mm (high myopia)?
- A) SRK/T formula
- B) Hoffer Q formula
- C) Haigis formula
- D) Barrett Universal II or Kane formula (modern AI-based formulas with superior performance across all axial lengths, including high myopia)
- E) SRK II formula
Answer: D
Rationale: IOL power calculation formula selection by axial length:
- Short eyes (<22 mm): Hoffer Q or Holladay 2 (historically); modern: Barrett Universal II or Kane
- Normal eyes (22-26 mm): All formulas perform well; SRK/T, Holladay 1, Hoffer Q, Barrett Universal II
- Long eyes (>26 mm): SRK/T was historically preferred, but modern consensus favors Barrett Universal II or Kane (AI-based) due to superior accuracy in extreme axial lengths
- Very long eyes (>30 mm): Barrett Universal II or Kane; SRK/T tends to over-minusify in extremely long eyes
The SRK II (E) is an obsolete 2nd-generation regression formula superseded by 3rd-generation (SRK/T) and now 4th-generation/AI formulas. For a 30.5 mm eye, Barrett Universal II and Kane have the best evidence for predictive accuracy.
Q20. What is the mechanism of malignant glaucoma (aqueous misdirection) and how does it differ from pupillary block glaucoma?
- A) Pupillary block due to swollen lens; treated with LPI and miotics
- B) Aqueous is misdirected posteriorly into the vitreous (misdirected anteriorly by ciliary processes) causing forward displacement of lens-iris diaphragm; LPI fails to deepen AC; anterior chamber is uniformly shallow; treated with cycloplegia + vitreous aspiration ± vitrectomy
- C) Suprachoroidal haemorrhage causing forward rotation of the lens-iris diaphragm
- D) Choroidal detachment causing globe softening and anterior chamber shallowing
- E) Angle closure from iris neovascularization in proliferative diabetic retinopathy
Answer: B
Rationale: Malignant glaucoma (aqueous misdirection, ciliary block glaucoma) is a rare but serious condition where aqueous is misdirected posteriorly into the vitreous (or anterior vitreous space), causing forward displacement of the entire lens-iris diaphragm. The defining feature: uniformly shallow AC in ALL quadrants (vs. pupillary block where the AC is shallow peripherally but deeper centrally, and the iris is bombe). A patent LPI fails to deepen the AC - this is pathognomonic. Treatment: cycloplegia (atropine) to tighten the ciliary body zonules and pull the lens back; carbonic anhydrase inhibitors; if refractory: Nd:YAG vitreolysis (hyaloid disruption) or pars plana vitrectomy. Occurs post-filtration surgery or after any intraocular surgery in susceptible eyes.
SECTION 4: UVEITIS, ORBIT & OCULOPLASTICS (Q21–25)
Q21. A 35-year-old Black woman presents with bilateral hilar lymphadenopathy on chest X-ray, erythema nodosum, and anterior uveitis with mutton-fat KPs and synechiae. Serum ACE is elevated. The most likely diagnosis and the ocular complication most associated with long-term visual morbidity are:
- A) Tuberculosis; optic nerve involvement
- B) Sarcoidosis; complicated cataract and secondary glaucoma from chronic uveitis
- C) HLA-B27 spondyloarthropathy; hypopyon
- D) Herpes zoster ophthalmicus; corneal scarring
- E) Fuchs heterochromic iridocyclitis; retinal detachment
Answer: B
Rationale: The combination of bilateral hilar lymphadenopathy, erythema nodosum, elevated ACE, and mutton-fat KPs (granulomatous uveitis with large greasy KPs) in a Black woman of reproductive age = sarcoidosis (Löfgren syndrome variant). Ocular sarcoidosis is present in 25-50% of systemic sarcoid. The most common causes of visual loss in chronic sarcoid uveitis: (1) complicated cataract from chronic inflammation and steroid treatment; (2) secondary glaucoma from trabecular meshwork infiltration and PAS; (3) cystoid macular oedema. Optic nerve granulomas, vitreous involvement ("snowball" opacities, "string of pearls"), peri-phlebitis, and neovascularization are also seen. Treatment: topical and systemic corticosteroids; steroid-sparing agents (methotrexate, azathioprine, mycophenolate) for chronic cases; anti-TNF for refractory cases.
Q22. An 8-year-old child is referred for strabismus evaluation. Cover-uncover test shows an esotropia that increases on left gaze. The left eye shows limited abduction. There is no A or V pattern. The head is turned to the right. This presentation is most consistent with:
- A) Divergence insufficiency
- B) Left medial rectus restriction (Duane type 1 left)
- C) Left lateral rectus paresis (VI nerve palsy)
- D) Right medial rectus overaction
- E) Consecutive exotropia after previous surgery
Answer: C
Rationale: Esotropia that worsens on gaze toward the affected side + limited abduction of that eye = VI nerve (abducens) palsy affecting the left lateral rectus. Key distinguishing feature from Duane syndrome: in a VI palsy, the forced duction test is negative (no restriction), whereas in Duane type 1 there is true fibrosis of the lateral rectus causing mechanical restriction on abduction. Additionally, Duane type 1 shows retraction of the globe and narrowing of the palpebral fissure on adduction (co-contraction), which is absent in a VI nerve palsy. Incomitant esotropia in a child with VI palsy warrants neuroimaging to exclude a pontine glioma, raised ICP, or other posterior fossa lesion.
Q23. A 55-year-old man presents with unilateral proptosis, diplopia, chemosis, and ocular bruit. IOP in the affected eye is 28 mmHg. There is arterialization of the episcleral vessels. The most likely diagnosis and its management are:
- A) Orbital cellulitis; IV antibiotics
- B) Orbital pseudotumour (IOIS); systemic steroids
- C) Carotid-cavernous fistula (CCF); interventional radiology with transarterial or transvenous embolization
- D) Thyroid eye disease; selenium and orbital decompression
- E) Lymphoma; biopsy and oncology referral
Answer: C
Rationale: The combination of proptosis + chemosis + ocular bruit + arterialized (red, corkscrew) episcleral vessels + elevated IOP is pathognomonic of a carotid-cavernous fistula (CCF). The bruit reflects high-flow arteriovenous shunting. Direct CCF (post-trauma, high-flow) vs. indirect/dural CCF (spontaneous, low-flow). Arterialization of episcleral veins reflects retrograde blood flow into the superior ophthalmic vein. IOP elevation is from raised episcleral venous pressure. Diagnosis: CT/MR angiography, confirmed by DSA. Treatment: interventional radiology - transarterial embolization for direct CCFs; transvenous coil embolization via the inferior petrosal sinus or superior ophthalmic vein for indirect CCFs.
Q24. A 9-year-old girl has a right esotropia of 30 PD at distance and near, with a full range of eye movements. She fixates with the left eye. Visual acuity right eye is 6/36, left eye 6/6. Cycloplegic refraction: right +4.50 DS, left +1.25 DS. What is the most likely diagnosis and first-line treatment?
- A) Divergence excess; prism glasses
- B) Fully accommodative esotropia with amblyopia; full hyperopic correction + patching therapy
- C) Non-accommodative convergence excess; surgery for the esotropia
- D) Duane syndrome type 3; observation
- E) Cyclic esotropia; botulinum toxin injection
Answer: B
Rationale: The scenario describes fully accommodative esotropia: (1) right hyperopia (+4.50 D) significantly greater than left (+1.25 D, explaining the preference for left eye fixation); (2) constant esotropia present at distance and near; (3) amblyopia in the more hyperopic eye (6/36 vs 6/6). Treatment principles: (1) Full cycloplegic hyperopic correction first - if the esotropia reduces to orthotropia with glasses, it is fully accommodative and glasses alone may straighten the eyes; (2) Patching/atropine penalisation of the sound eye to treat amblyopia (must be done urgently during the sensitive period); (3) If residual deviation persists despite full correction = partially accommodative component → surgical correction of the non-accommodative component.
Q25. A 70-year-old woman with a 6-month history of progressive painless bilateral proptosis, lid lag, and chemosis is referred. Thyroid function tests are normal. CT orbit shows enlarged extraocular muscles with tendon involvement. The most likely diagnosis is:
- A) Thyroid eye disease (TED/Graves orbitopathy)
- B) Orbital lymphoma
- C) Orbital myositis (idiopathic orbital inflammatory syndrome - IOIS)
- D) Carotid-cavernous fistula
- E) IgG4-related orbital disease
Answer: C
Rationale: The CT finding is the key discriminator: tendon involvement in muscle enlargement = orbital myositis (IOIS). In Thyroid Eye Disease (TED/Graves), the muscle belly enlarges but the tendons are characteristically spared - this is the classic CT distinction. In orbital myositis, the entire muscle including tendon is enlarged. Other features of IOIS/myositis: painful (TED is usually painless in chronic form), responds dramatically to oral steroids, can involve any orbital structure, may be associated with IgG4-RD. EOM enlargement order in TED (by frequency): Inferior rectus > Medial rectus > Superior rectus > Lateral rectus (mnemonic: I'M SLow). Option E (IgG4-RD) can cause orbital disease but typically involves the lacrimal gland and infraorbital nerve.
SECTION 5: REFRACTION, OPTICS & PHARMACOLOGY (Q26–30)
Q26. A patient has a prescription: Right eye: -4.00/-2.00 × 90. Converting this to plus cylinder notation gives:
- A) -6.00/+2.00 × 180
- B) -2.00/+2.00 × 90
- C) -6.00/+2.00 × 90
- D) -4.00/+2.00 × 180
- E) +2.00/-2.00 × 180
Answer: A
Rationale: To convert from minus to plus cylinder notation:
- New sphere = algebraic sum of old sphere and cylinder: -4.00 + (-2.00) = -6.00
- New cylinder = same magnitude with opposite sign: -2.00 → +2.00
- New axis = old axis ± 90°: 90° → 180°
Result: -6.00/+2.00 × 180
Cross-checks: Both notations describe the same lens. The two principal meridians have powers of -4.00 D (at 180°, the axis meridian) and -6.00 D (at 90°, the power meridian). The minus cylinder notation gives -4.00 at the axis (90°, meaning no cylinder power in that meridian), and -4.00 + (-2.00) = -6.00 at 90° from the axis. Both forms of notation are used clinically and conversion is tested extensively at fellowship level.
Q27. A 30-year-old pilot presents for refractive assessment. His manifest refraction is -5.00 DS OU, cycloplegic refraction is -3.00 DS OU. Near point of accommodation is at 10 cm. What is his amplitude of accommodation?
- A) 5 dioptres
- B) 10 dioptres
- C) 8 dioptres
- D) 3 dioptres
- E) 12 dioptres
Answer: B
Rationale: Amplitude of accommodation = Far point vergence - Near point vergence (in absolute terms).
- Far point of a -3.00 DS myope (using the corrected refraction): at optical infinity (distance = ∞; vergence = 0 D) with correct spectacle correction. The far point is 1/3.00 = 33.3 cm in front of the eye without correction. With correction, the far point is at infinity.
- Near point: 10 cm = vergence of 1/0.10 = 10 D from the eye
Amplitude of accommodation = 10 D - 0 D = 10 dioptres.
Using Hofstetter's formula: Expected amplitude for age 30 = 18.5 - (0.3 × 30) = 18.5 - 9 = 9.5 D (close to 10 D, consistent). Note: the manifest vs. cycloplegic discrepancy (-5.00 vs. -3.00) indicates 2 D of latent hyperopia masked by accommodation - a common examination finding.
Q28. A patient is receiving topical timolol 0.5% twice daily for POAG. She is subsequently prescribed systemic verapamil for hypertension by her cardiologist. What is the clinically significant interaction?
- A) Verapamil increases aqueous production, negating timolol's IOP-lowering effect
- B) Additive bradycardia and heart block risk: both timolol (non-selective beta-blocker) and verapamil (calcium channel blocker) slow cardiac conduction; concurrent use can cause severe bradycardia, AV block, or asystole
- C) Timolol induces cytochrome P450 metabolism of verapamil, reducing its antihypertensive effect
- D) Verapamil competes with timolol at the trabecular meshwork, reducing IOP-lowering effect
- E) The combination is safe; no clinically meaningful interaction exists
Answer: B
Rationale: Topical timolol, while applied to the eye, achieves significant systemic absorption (~60-80% of the dose) via nasolacrimal drainage, bypassing first-pass metabolism. Timolol is a non-selective beta-blocker that slows heart rate (SA node) and AV nodal conduction. Verapamil is a calcium channel blocker with negative chronotropic and dromotropic effects. The combination creates additive suppression of cardiac conduction → severe bradycardia, AV heart block, or even asystole. This interaction is particularly dangerous in elderly patients or those with pre-existing conduction abnormalities. Nasolacrimal duct occlusion (punctal occlusion) after drop instillation significantly reduces systemic absorption and should be recommended for all patients on topical timolol.
Q29. A patient on long-term hydroxychloroquine (400 mg/day) for systemic lupus erythematosus presents for routine ophthalmological monitoring. After 7 years of use and a cumulative dose of >1000g, which investigation is the MOST SENSITIVE for detecting early hydroxychloroquine retinopathy?
- A) Fundoscopy (looking for bull's eye maculopathy)
- B) Humphrey visual field (10-2 central threshold)
- C) Spectral-domain OCT (SD-OCT) showing parafoveal loss of the ellipsoid zone combined with multifocal electroretinogram (mfERG) or fundus autofluorescence (FAF)
- D) Fluorescein angiography (FA) showing bull's eye hyperfluorescence
- E) Colour vision testing (Farnsworth-Munsell 100 hue test)
Answer: C
Rationale: Current AAO screening guidelines (2016 revision) for hydroxychloroquine retinopathy emphasize that fundoscopy and visual fields alone miss early toxicity. The recommended screening battery for early detection includes: (1) SD-OCT - shows parafoveal thinning and loss of the photoreceptor ellipsoid zone (IS/OS junction) before symptoms or visual field changes; (2) mfERG - detects parafoveal cone dysfunction; (3) FAF - shows parafoveal hypoautofluorescence (RPE loss). The classic bull's eye maculopathy on fundoscopy and visual field scotoma represent advanced, often irreversible toxicity. Annual screening should begin after 5 years of use (or sooner in high-risk patients: daily dose >5 mg/kg ideal body weight, cumulative dose >1000g, renal disease, pre-existing macular disease).
Q30. A 25-year-old presents with acute unilateral painless loss of vision, RAPD, and a swollen optic disc. MRI shows demyelinating plaques in the periventricular white matter. Which clinical trial established that oral steroids alone are contraindicated as initial treatment?
- A) ONTT (Optic Neuritis Treatment Trial) — oral prednisone 1 mg/kg/day for 14 days INCREASED the rate of recurrent optic neuritis episodes
- B) CHAMPS trial — oral steroids equivalent to IV methylprednisolone
- C) BENEFIT trial — interferons should be started instead of any steroids
- D) AFFIRM trial — natalizumab prevents conversion to MS better than steroids
- E) PRISMS trial — subcutaneous interferon is the only effective treatment
Answer: A
Rationale: The ONTT (Optic Neuritis Treatment Trial) remains the landmark study for optic neuritis management. Its key findings: (1) IV methylprednisolone (1 g/day × 3 days) → speeds visual recovery but does NOT improve final visual acuity at 1 year; (2) Oral prednisone alone (1 mg/kg/day): no benefit over placebo for visual recovery AND significantly increased the rate of new attacks of optic neuritis - this arm was actually harmful; (3) Standard oral dose steroids are therefore contraindicated as primary treatment for acute optic neuritis. The MRI finding of periventricular plaques confers a high (~72%) 10-year risk of clinically definite MS - the CHAMPS trial showed high-dose IV steroids followed by beta-interferon delayed MS conversion in this high-risk group.
Summary Answer Key
| Q | Topic | Answer |
|---|---|---|
| 1 | LiGHT trial / SLT first-line | B |
| 2 | Fellow eye risk in APAC | C |
| 3 | APAC management - pilocarpine fallen from favour | D |
| 4 | Topiramate-induced angle closure | B |
| 5 | Sturge-Weber glaucoma mechanism | B |
| 6 | Krukenberg spindle - not pseudoexfoliation | D |
| 7 | Overfiltration / thin bleb complication | D |
| 8 | Symptomatic horseshoe tear | C |
| 9 | Lincoff's rule - bullous inferior RD | C |
| 10 | Centre-involving DMO treatment | B |
| 11 | DRS high-risk characteristics PDR | B |
| 12 | Cherry-red spot / CRAO emergency | B |
| 13 | CATT trial - bevacizumab vs ranibizumab | C |
| 14 | Pneumatic retinopexy indications | C |
| 15 | PCR during phacoemulsification | B |
| 16 | Cataract surgery + high CCT | B |
| 17 | Dense congenital cataract | B |
| 18 | YAG capsulotomy complications | B |
| 19 | IOL formula for high myopia | D |
| 20 | Malignant glaucoma mechanism | B |
| 21 | Sarcoid uveitis | B |
| 22 | VI nerve palsy vs Duane | C |
| 23 | Carotid-cavernous fistula | C |
| 24 | Accommodative esotropia + amblyopia | B |
| 25 | Orbital myositis - tendon involvement | C |
| 26 | Minus to plus cylinder conversion | A |
| 27 | Amplitude of accommodation | B |
| 28 | Timolol + verapamil interaction | B |
| 29 | Hydroxychloroquine screening | C |
| 30 | ONTT trial - oral steroids contraindicated | A |
Sources: Kanski's Clinical Ophthalmology 10e; Wills Eye Manual 8e; Goldman-Cecil Medicine; ETDRS, DRS, CATT, LiGHT, ONTT trial data
As an ophthalmologist preparing for post doctoral fellowship test my knowledge by asking advance level mcqs (50)on cornea
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I now have comprehensive source material. Let me compose all 50 fellowship-level MCQs.
As an ophthalmologist preparing for post doctoral fellowship test my knowledge by asking advance level mcqs (50)on cornea
Finding Sources
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I now have comprehensive, verified source material from Kanski's Clinical Ophthalmology 10e and Wills Eye Manual 8e covering all major corneal topics. Let me now deliver all 50 fellowship-level MCQs.
Advanced Cornea — 50 Fellowship MCQs
Source: Kanski's Clinical Ophthalmology 10e | Wills Eye Manual 8e
SECTION 1: CORNEAL ANATOMY, PHYSIOLOGY & OPTICS (Q1–5)
Q1. The normal central corneal thickness (CCT) is approximately 540 μm. Which layer of the cornea contributes the most to overall corneal thickness?
- A) Epithelium (50 μm)
- B) Bowman layer (15 μm)
- C) Stroma (~500 μm; ~90% of total thickness)
- D) Descemet membrane (10-12 μm in adults)
- E) Endothelium (5 μm monolayer)
Answer: C
Rationale: The corneal stroma comprises approximately 90% of the total corneal thickness (~500 μm of the ~540 μm total). It consists of roughly 300 orthogonally arranged lamellae of collagen type I fibrils (synthesized by keratocytes), maintained at precise 22-32 nm interfibril spacing by proteoglycans (lumican, keratocan, mimecan - all keratan sulfate proteoglycans) that confer optical transparency. This architecture is disrupted in macular corneal dystrophy (CHST6 mutation affecting KS sulfation), explaining the characteristic diffuse clouding. For fellowship examiners: the precise fibril spacing is maintained by negative charges on the proteoglycan side chains repelling each other electrostatically.
Q2. The corneal endothelium maintains corneal clarity primarily through which mechanism, and what is the minimum endothelial cell density (ECD) generally considered necessary to maintain corneal decompensation-free clarity?
- A) Active Na/K-ATPase pump that moves Na⁺ (and water following osmotically) from stroma to aqueous; minimum ECD ~400-500 cells/mm²
- B) Passive diffusion barrier only; minimum ECD ~1000 cells/mm²
- C) Active Cl⁻ secretion driving fluid into stroma; minimum ECD ~2000 cells/mm²
- D) Active bicarbonate (HCO₃⁻) pump moving fluid into anterior chamber combined with a tight junction barrier; minimum ECD ~500-700 cells/mm²
- E) Active water channel (aquaporin-1) pump; minimum ECD ~300 cells/mm²
Answer: D
Rationale: The corneal endothelium maintains dehydration and transparency through two complementary mechanisms: (1) tight junctions (zonula occludens between cells) acting as a partial barrier to aqueous influx; and (2) active metabolic pump - primarily a bicarbonate-dependent (HCO₃⁻) Na/K/ATPase that transports fluid from stroma to aqueous humour. The HCO₃⁻ pump (bicarbonate transport via carbonic anhydrase and SLC4A11) is considered the primary driver. The minimum ECD for corneal transparency is debated but generally placed at ~500-700 cells/mm²; below this, decompensation typically occurs. Normal adult ECD is ~2500-3000 cells/mm²; endothelial cells do not regenerate in vivo (G1 cell cycle arrest maintained partly by ROCK pathway).
Q3. Corneal transparency requires that light scatter be minimized. The primary optical basis for corneal transparency is:
- A) Absence of blood vessels and melanin pigment
- B) Precise short-range order (lattice arrangement) of collagen fibrils with uniform 22-30 nm spacing, creating destructive interference of scattered light waves
- C) High water content allowing uniform refractive index throughout
- D) Collagen lamellae perpendicular to each other eliminating birefringence
- E) High concentration of crystallin proteins absorbing scattered light
Answer: B
Rationale: The Maurice lattice theory (1957) explains corneal transparency: stromal collagen fibrils are arranged with short-range lattice order at nearly uniform spacing (~22-30 nm apart). This regular arrangement means that scattered light from individual fibrils undergoes destructive interference (the scattered waves cancel each other out) while transmitted light is reinforced. Disruption of this spacing (by edema, scars, dystrophy deposits) allows light scatter and opacity. When the stroma swells >500 μm above normal, the fibril spacing becomes irregular, and transparency is lost - explaining morning corneal clouding in Fuchs dystrophy and the clarity threshold for surgical decisions.
Q4. A 35-year-old myope is found on corneal topography to have superior steepening with oblique astigmatism and inferior flattening. The pattern is described as a "crab-claw" on topography. What is this pattern called and what does it represent?
- A) Keratoconus - classic cone with inferotemporal displacement
- B) Pellucid marginal degeneration - "butterfly" topographic pattern from inferior thinning causing against-the-rule astigmatism with superior steepening
- C) Contact lens warpage - oblique astigmatism from RGP lens effect
- D) Keratoglobus - generalized steepening from global ectasia
- E) Posterior polymorphous corneal dystrophy - endothelial irregularity causing surface distortion
Answer: B
Rationale: The "butterfly" or "crab-claw" pattern on topography is characteristic of pellucid marginal degeneration (PMD). In PMD, a band of inferior corneal thinning (4 to 8 o'clock, 1-2 mm from limbus) causes the cornea above the thinned area to ectase (not the thinned area itself), producing superior steepening and a classic high against-the-rule or oblique astigmatism. Topography shows diffuse steepening inferiorly with two "horns" of steepening reaching superolaterally - the butterfly/crab-claw appearance. Key distinction from keratoconus: PMD thinning is peripheral (inferior), no Fleischer ring, no Vogt striae, and acute hydrops is rare in PMD.
Q5. In assessing a patient for LASIK, which topographic finding is considered most suspicious for subclinical keratoconus (forme fruste keratoconus)?
- A) Symmetric "bow-tie" astigmatism pattern with equal superior and inferior power
- B) Inferior-superior (I-S) dioptric asymmetry > 1.4 D, posterior elevation above best-fit sphere > 15-16 μm, and thinnest point displacement from centre
- C) Regular oblique astigmatism with no central ectasia
- D) Mild with-the-rule astigmatism (<1.0 D) with symmetric corneal power
- E) Slight superior steepening representing normal anatomical variation
Answer: B
Rationale: Screening for forme fruste keratoconus before refractive surgery is one of the most important applications of corneal topography/tomography. Pentacam (Scheimpflug) tomography criteria for subclinical KC include: (1) Posterior elevation above best-fit sphere > 15-16 μm on the posterior float map (posterior surface is the most sensitive early indicator, as KC starts in the posterior stroma); (2) Inferior-superior (I-S) asymmetry > 1.4 D on anterior curvature; (3) Thinnest point displacement inferolaterally from the corneal apex; (4) Belin-Ambrósio (BAD) D-value > 1.6. Kanski 10e emphasises: "Patients should be screened for KC prior to corneal refractive surgery" and "LASIK is contraindicated."
SECTION 2: KERATOCONUS & CORNEAL ECTASIAS (Q6–12)
Q6. A 19-year-old male presents with progressive myopia and astigmatism over 2 years. Keratometry reads 52 D steepest meridian. Retinoscopy shows a scissoring reflex. He has Down syndrome and a habit of eye rubbing. Slit-lamp shows Vogt striae, a Fleischer ring, and central anterior stromal thinning. What grade of keratoconus is this, and what is the current evidence-based treatment to halt progression?
- A) Mild KC (<48 D); observation
- B) Moderate KC (48-54 D); corneal collagen crosslinking (CXL) with riboflavin + UV-A, which is successful in halting progression in >90% of cases
- C) Severe KC (>54 D); immediate DALK
- D) Mild KC; intrastromal ring segment implantation
- E) Moderate KC; LASIK to regularize the astigmatism
Answer: B
Rationale: Keratometry 52 D = moderate KC (48-54 D). Current gold-standard treatment for documented progression is corneal collagen crosslinking (CXL) - riboflavin (vitamin B2) photosensitizer drops applied to epithelium-debrided cornea followed by UV-A (370 nm, 3 mW/cm²) for 30 minutes. Riboflavin + UV-A generates free radicals that form new covalent bonds (pyridinium crosslinks) between collagen fibrils, stiffening the stroma and halting ectasia progression. Kanski 10e: "CXL is successful in more than 90% of cases and in some cases can even reverse the ectasia." Down syndrome is a recognised systemic association. LASIK is absolutely contraindicated in any form of KC. Eye rubbing is the most modifiable risk factor and must be actively discouraged.
Q7. A 22-year-old with advanced keratoconus (K > 60 D) and intolerance to rigid contact lenses is referred for surgical management. He gives a history of "red, painful eye with sudden vision loss" 1 year ago that resolved with scarring. Which surgical option is CONTRAINDICATED due to this history?
- A) Penetrating keratoplasty (PKP)
- B) Deep anterior lamellar keratoplasty (DALK)
- C) Scleral contact lens fitting prior to surgery
- D) Intracorneal ring segment implantation
- E) Corneal collagen crosslinking
Answer: B
Rationale: The history of sudden painful red eye with vision loss resolving with scarring = acute hydrops (rupture of Descemet membrane allowing aqueous ingress into stroma). Kanski 10e explicitly states: "A history of hydrops is a contraindication to DALK due to the presence of a Descemet membrane discontinuity." DALK requires a continuous, intact Descemet membrane to achieve the "big bubble" plane of dissection; a prior DM break/scar prevents this. PKP is the appropriate surgical option for KC with prior hydrops (option A). DALK's major advantage in KC - avoiding endothelial rejection risk - cannot be utilised when DM integrity is compromised.
Q8. Regarding DALK vs. PKP for keratoconus WITHOUT prior hydrops, which statement is most accurate?
- A) PKP gives superior final visual acuity compared to DALK in all cases
- B) DALK eliminates the risk of endothelial rejection, uses donor tissue with irrelevant endothelial quality (expanding tissue availability), results in a structurally stronger globe, and achieves less astigmatism than PKP, though interface haze may limit final BCVA
- C) DALK requires shorter suture retention time than PKP (12-18 months vs. 6 months)
- D) DALK has a higher graft rejection rate than PKP because the interface creates more antigen exposure
- E) DALK should not be performed in patients with vernal keratoconjunctivitis due to the risk of graft infection
Answer: B
Rationale: Kanski 10e lists DALK advantages: (1) No endothelial rejection risk (endothelium is not transplanted); (2) Increased graft availability - endothelial cell quality of donor is irrelevant; (3) Structurally stronger globe (full-thickness recipient eye is not opened); (4) Less astigmatism compared to PKP. Disadvantage: interface haze may limit final BCVA; technically very demanding with risk of DM perforation. Note: DALK does still carry risk of epithelial/stromal rejection (but NOT endothelial). Sutures in DALK can be removed earlier (6 months) vs. 12-18 months in PKP (option C is reversed). Vernal keratoconjunctivitis actually carries increased graft rejection risk (option E) - not infection, and DALK is actually preferred in atopic/VKC patients precisely because of the lower rejection risk (Kanski: "Chronic inflammatory disease such as atopic keratoconjunctivitis carries an increased risk of graft rejection").
Q9. A keratoconus patient has central apical scarring but a deep clear stroma and a normal endothelium. He does not have a history of hydrops. Corneal tomography shows the thinnest point as 380 μm. What is the IDEAL surgical option?
- A) PKP, as apical scarring mandates full-thickness replacement
- B) DALK using the big-bubble (Anwar) technique - removes anterior 95% of corneal stroma including the scar, preserves the host endothelium, uses donor stroma to the level of DM
- C) Superficial PTK to remove the scar, then DALK later
- D) DSAEK as the endothelium may be stressed by the ectasia
- E) Automated lamellar therapeutic keratoplasty (ALTK)
Answer: B
Rationale: In KC with anterior apical scarring but intact DM and normal endothelium (no history of hydrops), DALK using the Anwar "big bubble" technique is ideal. The big-bubble technique involves injecting air into the pre-Descemet's plane to separate the posterior stroma from DM, creating a pneumatic dissection plane to DM level. This removes all diseased anterior stroma (including the scar) while preserving the host's DM and endothelium. DSAEK/DMEK (D) replaces the endothelium and is used for endothelial disease, not appropriate here. Kanski: DALK is indicated for "disease involving the anterior 95% of corneal thickness with normal endothelium and the absence of breaks or scars in Descemet membrane."
Q10. Pellucid marginal degeneration (PMD) differs from keratoconus in several key ways. Which statement about PMD is INCORRECT?
- A) The thinning in PMD is peripheral, typically from 4 to 8 o'clock, 1 mm from the limbus
- B) The cornea ectases and steepens ABOVE the thinned area (not at the thinning site itself)
- C) Fleischer rings and Vogt striae are common features of PMD, identical to keratoconus
- D) Acute hydrops is rare in PMD compared to keratoconus
- E) Topography shows a characteristic butterfly/crab-claw pattern
Answer: C
Rationale: Kanski 10e explicitly states: "In contrast to keratoconus, Fleischer rings and Vogt striae do not occur and acute hydrops is rare" in PMD. Fleischer ring (iron deposition at the base of the cone in the epithelium) and Vogt striae (fine stress lines in deep stroma parallel to the steep corneal meridian) are hallmarks of keratoconus and are NOT seen in PMD. This is a key distinguishing clinical feature. Options A, B, D, and E are all correct descriptions of PMD.
Q11. Keratoglobus differs from keratoconus in which important clinical aspect?
- A) Keratoglobus only occurs in adults
- B) Keratoglobus involves generalised corneal thinning with globular (not conical) ectasia; it is more prone to rupture from mild trauma; acute hydrops is rare
- C) Keratoglobus is more commonly associated with Down syndrome than keratoconus
- D) Keratoglobus responds excellently to corneal collagen crosslinking
- E) Keratoglobus has a better visual prognosis with rigid contact lenses than keratoconus
Answer: B
Rationale: Kanski 10e: "Keratoglobus...the cornea develops globular rather than conical ectasia and is associated with generalised corneal thinning. Acute hydrops is rare, but the cornea is more prone to rupture on relatively mild trauma." Keratoglobus can be congenital or acquired; congenital cases must be differentiated from congenital glaucoma (large cornea due to elevated IOP) and megalocornea. Its associations include: Ehlers-Danlos syndrome (type VI), Leber congenital amaurosis, rubella keratopathy, and steroid-induced. CXL has limited evidence in keratoglobus because the thinning is generalised and not focal. The extreme thinning makes surgery very high risk.
Q12. Corneal collagen crosslinking (CXL): regarding the "accelerated" vs. "standard" Dresden protocol, which statement is most clinically accurate for a patient with progressive KC and a thinnest corneal point of 375 μm?
- A) Both accelerated and standard CXL are safe at any corneal thickness
- B) The Dresden protocol (standard CXL: 3 mW/cm² for 30 min, total 5.4 J/cm²) is the gold standard; a corneal thickness of ≥400 μm at the time of epithelial removal is the minimum safe threshold to avoid endothelial damage from UV-A penetration
- C) The corneal thickness criterion is irrelevant because UV-A does not penetrate beyond the anterior stroma
- D) Accelerated CXL (45 mW/cm² for 1 minute, same total fluence) has proven superior efficacy compared to standard Dresden protocol
- E) Contact lens-assisted CXL (CACXL) is not recommended as it produces uneven riboflavin absorption
Answer: B
Rationale: The Dresden protocol (standard CXL) remains the benchmark: riboflavin 0.1% drops every 2 minutes for 20-30 minutes on de-epithelialized cornea, then UV-A at 3 mW/cm² for 30 minutes (total 5.4 J/cm²). The minimum corneal thickness of ≥400 μm after epithelial debridement is the established safety threshold, because the UV-A must be absorbed within the anterior 300-400 μm to protect the endothelium. If the cornea is <400 μm, hypotonic riboflavin is used first to swell the cornea to ≥400 μm. For this patient at 375 μm, hypotonic riboflavin should be used to reach the safety threshold before UV-A application. Accelerated CXL (higher intensity, shorter time) has shown similar efficacy but potentially less depth of crosslinking in some studies.
SECTION 3: INFECTIOUS KERATITIS (Q13–24)
Q13. A 28-year-old daily soft contact lens wearer presents with 3 weeks of worsening left eye pain "out of proportion" to the clinical signs, with photophobia and redness. She swims regularly with lenses in. Slit-lamp shows pseudodendrites and early subepithelial infiltrates along corneal nerve tracks. Bacterial cultures are negative. What is the most likely diagnosis, and what stain is MOST SPECIFIC for the causative organism?
- A) HSV epithelial keratitis; Giemsa stain for multinucleated giant cells
- B) Acanthamoeba keratitis; Calcofluor white (fluorescent dye with affinity for amoebic cysts and fungi) or PAS stain demonstrating cysts
- C) Fungal keratitis; KOH smear and Gomori methenamine silver
- D) Bacterial keratitis with ring ulcer; Gram stain
- E) Thygeson superficial punctate keratitis; no organism identified
Answer: B
Rationale: The combination of: contact lens wear + swimming with lenses + pain disproportionate to signs + pseudodendrites + radial keratoneuritis (infiltrates along corneal nerve tracts - virtually pathognomonic) + negative bacterial cultures = Acanthamoeba keratitis. Diagnosis: corneal scraping stained with calcofluor white (fluorescent dye binding chitin in amoebic cyst wall) or PAS stain to visualize cysts; Gram and Giemsa may also show cysts. Culture on non-nutrient agar seeded with dead E. coli is the gold standard culture method (trophozoites consume the bacteria). In vivo confocal microscopy (IVCM) is an increasingly used non-invasive diagnostic modality showing highly reflective cysts. PCR is also available.
Q14. In Acanthamoeba keratitis, the FIRST-LINE treatment regimen recommended in the UK and widely used globally is:
- A) Topical natamycin 5% hourly + oral voriconazole
- B) Topical polyhexamethylene biguanide (PHMB) 0.02% + chlorhexidine 0.02%, both given intensively (every 1-2 hours), often combined with a biguanide-diamidine combination, continued for minimum 3 months after resolution
- C) Topical acyclovir 3% ointment 5 times daily
- D) Topical ciprofloxacin 0.3% + systemic fluconazole
- E) Immediate corneal transplantation before medical therapy
Answer: B
Rationale: Acanthamoeba keratitis treatment targets both trophozoite and cyst forms (cysts are highly resistant). First-line dual therapy: PHMB 0.02% (polyhexamethylene biguanide) + propamidine isethionate (Brolene) 0.1% or chlorhexidine 0.02%, given intensively every 1-2 hours initially. These disrupt cell membranes of both forms. Treatment is prolonged - 3 months after clinical resolution of inflammation (total treatment may be 6-12 months). Wills Eye Manual additionally mentions miltefosine (an oral antiprotozoal) and notes rebound inflammation after stopping miltefosine may respond to topical steroids. Steroids should be avoided BEFORE specific treatment is established (Kanski: "avoiding the use of corticosteroids before commencing specific treatment" is key to good outcomes). Corneal transplant is delayed 6-12 months after medical treatment completion to reduce recurrence risk.
Q15. A 50-year-old farmer presents with a corneal ulcer 5 days after being struck in the eye by a paddy plant. The infiltrate has a grey-white appearance with feathery borders and satellite lesions. There is a hypopyon. The most likely causative organism, its diagnostic stain, and primary treatment are:
- A) Pseudomonas aeruginosa; Gram stain (Gram-negative rods); fluoroquinolone monotherapy
- B) Fusarium or Aspergillus species (filamentous fungi); KOH smear, calcofluor white, Gomori methenamine silver; topical natamycin 5% as first-line
- C) Herpes simplex; Giemsa stain; topical ganciclovir
- D) Acanthamoeba; PAS stain; PHMB
- E) Staphylococcus aureus; Gram stain (Gram-positive cocci); cefazolin
Answer: B
Rationale: Vegetable matter trauma (especially paddy/plant material in tropical/agricultural settings) + feathery borders + satellite lesions = filamentous fungal keratitis (Fusarium spp. most common globally; Aspergillus in temperate regions). Wills Eye Manual: "infiltrates commonly have feathery borders and/or may be surrounded by satellite lesions" in filamentous fungi. The infiltrate in fungal keratitis characteristically extends beyond the epithelial defect (unlike bacterial). Diagnosis: corneal scraping stained with KOH (dissolves cellular debris, revealing hyphae), calcofluor white (binds fungal cell walls), Gomori methenamine silver or PAS. Topical natamycin 5% (polyene antifungal) is first-line for filamentous fungi, superior to azoles. Voriconazole (systemic/topical) for refractory cases. Deep infiltrates may require intrastromal or intracameral antifungal injection.
Q16. Candida corneal ulcer characteristically differs from Fusarium ulcer in which way?
- A) Candida causes feathery borders and satellite lesions, Fusarium causes dense smooth infiltrate
- B) Candida typically occurs in previously diseased eyes (dry eyes, chronic steroid use, herpes keratitis, immunosuppression) and produces a grey-white infiltrate similar to bacterial ulcers; Fusarium occurs in previously healthy eyes after trauma
- C) Candida requires Gomori methenamine silver stain, Fusarium requires only KOH
- D) Candida responds to natamycin, Fusarium requires fluconazole
- E) Both organisms have identical clinical presentations and require the same treatment
Answer: B
Rationale: Wills Eye Manual distinguishes: Filamentous fungi (Fusarium, Aspergillus) occur typically after trauma in previously healthy eyes and show feathery borders/satellite lesions. Candida (nonfilamentous) usually occurs in eyes with pre-existing ocular surface disease: dry eye, chronic steroid use, HSV/VZV keratitis, exposure keratopathy, immunosuppression. Candida keratitis may clinically mimic a bacterial ulcer (round, dense infiltrate without feathery borders). Both types show similar diagnostic stains (KOH, calcofluor white, Gomori MS, PAS). Treatment: natamycin is better for filamentous; azoles (fluconazole, voriconazole) may have better activity against Candida.
Q17. A 32-year-old contact lens wearer has a dendritic corneal lesion. Which single clinical feature most reliably DISTINGUISHES a true HSV dendrite from Acanthamoeba pseudodendrites?
- A) Size of the lesion (HSV is larger)
- B) Time course (HSV is faster)
- C) HSV dendrites are true epithelial ulcerations with terminal end-bulbs, staining centrally with fluorescein and marginally with rose bengal/lissamine green; Acanthamoeba pseudodendrites are raised epithelial lesions (not ulcerations), without true terminal bulbs
- D) HSV occurs only in non-contact lens wearers
- E) Pain severity (Acanthamoeba is painless, HSV is extremely painful)
Answer: C
Rationale: Wills Eye Manual: "A 'true' dendrite (branching epithelial ulceration with terminal end-bulbs) is pathognomonic for HSV." The edges of HSV dendrites are heaped with swollen epithelial cells staining with rose bengal/lissamine green (indicating devitalized cells); the central ulcer bed stains with fluorescein. Acanthamoeba pseudodendrites are raised epithelial lesions (not ulcerations) without true terminal bulbs - they represent living amoeba-infested epithelium, NOT necrosis. VZV pseudodendrites are similarly elevated, without central ulceration, and do NOT stain well with fluorescein. This distinction is critical because misdiagnosing Acanthamoeba as HSV and treating with antivirals leads to clinical deterioration.
Q18. HSV stromal keratitis WITHOUT epithelial ulceration (immune/non-necrotising stromal keratitis) is best described as:
- A) Active viral replication in the stroma requiring antiviral monotherapy
- B) An immune-mediated reaction (not active replication) to viral antigens, treated with topical steroids (prednisolone acetate 1% up to 8x/day, tapered slowly) plus prophylactic oral antiviral (acyclovir 400 mg BD or valacyclovir 500 mg OD)
- C) Bacterial superinfection requiring broad-spectrum antibiotics
- D) A direct extension of epithelial HSV requiring debridement and antiviral
- E) Treated identically to HSV epithelial keratitis with topical trifluridine
Answer: B
Rationale: Wills Eye Manual: "HSV stromal keratitis is considered an immune reaction rather than active infectious process and therefore treatment is directed accordingly." Treatment paradigm: topical steroids (therapeutic dose, tapered very slowly - patients may need low-dose maintenance indefinitely) + prophylactic oral antiviral throughout steroid therapy. This is supported by the HEDS (Herpetic Eye Disease Study) trials, which showed steroids accelerate resolution and reduce progression to worse disease, and oral acyclovir reduces recurrences. The oral antiviral is critical because steroids could allow viral replication in the absence of antiviral cover. Contrast with HSV epithelial keratitis (active virus) which uses ANTIVIRAL WITHOUT steroids (steroids promote geographic ulceration).
Q19. The HEDS (Herpetic Eye Disease Study) established the role of oral acyclovir in HSK management. Regarding long-term prophylaxis for recurrent HSK, which statement is correct?
- A) Oral acyclovir has no proven benefit in reducing recurrence frequency
- B) Long-term oral acyclovir (400 mg BD) reduces the frequency of all forms of recurrent HSK (epithelial, stromal, and iritis) by approximately 41-45%, and should be considered in patients with ≥2 recurrences per year or severe disease
- C) Topical antiviral (ganciclovir gel) is equally effective as oral acyclovir for long-term prevention
- D) Prophylaxis should only be given in immunocompromised patients
- E) Treatment should be stopped after 2 years as no additional benefit accrues
Answer: B
Rationale: The HEDS Acyclovir Prevention Trial demonstrated that oral acyclovir 400 mg BD reduced the rate of recurrent HSK by 41-45% over 12 months. Benefits were shown for ALL forms of recurrent HSK. Kanski: "Prophylactic oral aciclovir (400 mg twice daily) improves graft survival and should be given to patients undergoing penetrating keratoplasty for herpetic eye disease." Indications for long-term prophylaxis: ≥2 recurrences/year, severe stromal disease, history of bilateral disease, post-keratoplasty for herpetic disease, severely immunocompromised. Treatment is continued indefinitely for high-risk patients; some centres continue for many years.
Q20. A patient with HZO (herpes zoster ophthalmicus) involving the V1 dermatome develops a painless corneal ulcer 6 months after the acute episode. There is reduced corneal sensation, the ulcer is oval with smooth edges and no stromal infiltrate, and there is no mucopurulent discharge. What is the diagnosis and mechanism?
- A) Bacterial superinfection; treat with broad-spectrum antibiotics
- B) Disciform keratitis; treat with topical steroids
- C) Neurotrophic keratopathy (Mackie stage 2-3) caused by viral destruction of trigeminal sensory nerve fibres → loss of corneal sensation → epithelial breakdown, poor healing, progressive ulceration
- D) HSV superinfection; treat with acyclovir
- E) Exposure keratopathy from lagophthalmos; treat with lubricants and lid surgery
Answer: C
Rationale: HZO characteristically causes corneal anaesthesia through necrosis and inflammation of the trigeminal (nasociliary) ganglion and its peripheral branches. This leads to neurotrophic keratopathy - a trophic ulcer that develops because the epithelium lacks the neurotrophic growth factors normally provided by intact corneal innervation (substance P, IGF-1, etc.). The Mackie classification: Stage 1 = epithelial irregularity; Stage 2 = persistent epithelial defect; Stage 3 = stromal ulceration with risk of perforation. Key features: no infection, no infiltrate, smooth "punched-out" margins, central/inferocentral location, absent or reduced corneal sensation. Treatment: cenegermin (recombinant human nerve growth factor, Oxervate) is the first approved treatment; also preservative-free lubricants, BCL, punctal occlusion, autologous serum, partial tarsorrhaphy.
Q21. Regarding bacterial keratitis management, which of the following correctly describes the contemporary approach to culture and treatment?
- A) All cases of suspected bacterial keratitis must be cultured before treatment; antibiotics should be withheld until results are available
- B) Corneal scraping for Gram stain and culture (blood agar, chocolate agar, Sabouraud's, thioglycolate broth) should be performed for any ulcer meeting criteria (central, >1 mm, severe, immunocompromised, atypical, CL-associated); empirical broad-spectrum topical fluoroquinolone monotherapy (ciprofloxacin 0.3% or moxifloxacin 0.5%) is acceptable as first-line while awaiting cultures
- C) Culture is only necessary if the patient fails to respond to 48 hours of antibiotics
- D) Topical chloramphenicol is the current gold standard first-line antibiotic
- E) All contact lens-related ulcers must be treated with dual-drug therapy (cephalosporin + aminoglycoside) regardless of size
Answer: B
Rationale: Wills Eye Manual approach: corneal scraping with multiple samples (for Gram, Giemsa, calcofluor white, and culture on multiple media) for ulcers that are: central location, >1-2 mm infiltrate, severe stromal involvement, not contact lens-related marginal infiltrate, immunocompromised host, atypical appearance, or unresponsive to prior treatment. Empirical treatment: fluoroquinolone monotherapy (ciprofloxacin 0.3%, ofloxacin 0.3%, or moxifloxacin 0.5%) is the standard of care for most bacterial keratitis cases and provides equivalent coverage to the older "fortified" two-drug regimen (cefazolin + tobramycin) in most studies. Small, peripheral, contact-lens-related ulcers with mild signs may be treated empirically without scraping.
Q22. Crystalline keratopathy is a distinct form of infectious keratitis. What is the classic organism responsible, its predisposing condition, and its appearance?
- A) Pseudomonas aeruginosa in contact lens wearers; dense white consolidation
- B) Streptococcus viridans (α-haemolytic streptococci) in the setting of long-term topical steroid use (especially post-keratoplasty); needle-like or branching crystalline opacities in the anterior-mid stroma without overlying epithelial defect or inflammatory signs (because steroids suppress the inflammatory response)
- C) Candida albicans in immunocompromised patients; white fluffy colonies at the junction
- D) Acanthamoeba in contact lens wearers; ring-shaped infiltrate
- E) Nocardia asteroides; filamentous hyphae in deep stroma
Answer: B
Rationale: Wills Eye Manual describes crystalline keratopathy: "crystals seen in subepithelial and/or stromal regions of the cornea." The classic organism is Streptococcus viridans (α-haemolytic Streptococcus), though other organisms (including fungi - Candida, and Haemophilus) are described. The classic setting is post-keratoplasty patients on chronic topical steroids - steroids suppress the inflammatory response, allowing organisms to proliferate slowly and lay down crystalline protein deposits without the usual signs of inflammation. The appearance: fine needle-like or dendritic crystalline opacities in the stroma, no overlying epithelial defect in early cases, no discharge, no significant injection. Diagnosis is confirmed by corneal biopsy (superficial scraping is often negative). Treatment: vigorous topical antibiotics (penicillin, moxifloxacin) with steroid reduction.
Q23. Microsporidial keratitis is emerging as a cause of keratoconjunctivitis. What are the two distinct clinical forms and their associated host immune status?
- A) Superficial keratoconjunctivitis (diffuse PEK) in immunocompetent patients and deep stromal keratitis in immunocompromised (HIV/AIDS) patients; both forms caused by Encephalitozoon species
- B) Only affects immunocompromised patients in both forms
- C) Deep stromal keratitis is the common form in normal hosts
- D) Microsporidiosis is exclusively an enteric disease with no ocular involvement
- E) Superficial keratitis in HIV patients and deep stromal keratitis in immunocompetent patients
Answer: A
Rationale: Kanski 10e: Microsporidia are "obligate intracellular single-celled parasites previously thought to be protozoa but now reclassified as fungi." Two distinct ocular forms: (1) Diffuse superficial punctate keratoconjunctivitis - seen in immunocompetent patients (contact lens wearers, after water exposure), self-limiting, responds to fumagillin or albendazole; (2) Deep stromal keratitis - seen in immunocompromised patients (HIV/AIDS, transplant recipients), more serious, may require keratoplasty. In the AIDS era, microsporidial keratitis was a significant opportunistic infection. The distinction between superficial (immune-competent host) and deep (immune-compromised host) presentation is a key fellowship discriminator.
Q24. A patient is referred with Thygeson superficial punctate keratitis (TSPK). Which combination of clinical features is PATHOGNOMONIC of this condition?
- A) Diffuse PEK with papillary conjunctivitis, mucopurulent discharge, Gram-positive cocci on scraping
- B) Bilateral coarse stellate epithelial opacities (raised, irregular, snowflake-like) with no conjunctival inflammation, waxing and waning course over years, no identifiable organism, reduced corneal sensation, responds to low-dose topical steroids or CsA; normal between recurrences
- C) Dendritic ulcers with terminal bulbs, positive for HSV PCR
- D) Fine diffuse PEK with trachomatous follicles, superior pannus, chlamydial PCR positive
- E) Bilateral limbal follicles with epidemic spread and pre-auricular lymphadenopathy
Answer: B
Rationale: Thygeson SPK (Wills Eye Manual 4.8) is an unusual, chronic, recurrent epithelial keratitis of unknown aetiology (possibly viral, possibly immune-mediated). Classic features: bilateral coarse stellate/snowflake-like elevated epithelial opacities (not a true ulcer); no conjunctival inflammation (the absence of any conjunctivitis is a key distinguishing feature); white-light appearance: opacities appear greyish-white on direct illumination, glistening on retroillumination; waxing and waning over many years; culture/PCR negative; may have mildly reduced sensation; responds to low-dose topical steroids (prednisolone 0.12% QID), cyclosporine A 0.05-1%, or bandage contact lens for comfort. Does NOT respond to antivirals despite initial misdiagnosis as HSV.
SECTION 4: CORNEAL DEGENERATION & OCULAR SURFACE DISEASE (Q25–32)
Q25. Band keratopathy is calcium hydroxyapatite deposition in Bowman layer. In the interpalpebral zone, it characteristically shows a clear zone at the limbus (separated from the limbus by a clear zone). Which condition is associated with METABOLIC (hypercalcaemia-related) band keratopathy?
- A) Chronic uveitis in juvenile idiopathic arthritis
- B) Hyperparathyroidism, vitamin D toxicity, milk-alkali syndrome, sarcoidosis, end-stage renal disease, and Paget disease
- C) Silicone oil tamponade
- D) Gout (hyperuricaemia)
- E) Ichthyosis
Answer: B
Rationale: Kanski 10e categorises band keratopathy causes: Ocular (most common overall): chronic uveitis (JIA most common in children), phthisis, silicone oil. Metabolic (metastatic calcification from hypercalcaemia): hyperparathyroidism, vitamin D toxicity, milk-alkali syndrome, sarcoidosis, end-stage renal disease, Paget disease. Hyperuricaemia is a rare cause of band keratopathy distinct from calcium deposition. Treatment: EDTA chelation (1.5-3% EDTA applied after epithelial removal) is simple and effective for mild cases. More severe cases: diamond burr, excimer PTK, or lamellar keratoplasty. The clinical hallmark: calcium deposition progresses in the interpalpebral zone (3-9 o'clock) with characteristic "swiss cheese" holes (corresponding to Bowman layer perforations where corneal nerves penetrate) and a clear zone separating the band from the limbus.
Q26. A 70-year-old man presents with bilateral bilateral whitish peripheral corneal opacification. Slit-lamp shows a 1 mm wide band separated from the limbus by a clear zone, with the superior and inferior cornea first involved. He is otherwise healthy. The finding is:
- A) Band keratopathy - suggests hypercalcaemia workup required
- B) Arcus senilis (gerontoxon) - physiological lipid deposition, full lipid screen only if age <50 years (arcus juvenilis)
- C) Pellucid marginal degeneration - requires corneal topography
- D) Salzmann nodular degeneration - requires superficial keratectomy
- E) Terrien marginal degeneration - requires urgent surgical management
Answer: B
Rationale: Kanski: arcus senilis involves "stromal lipid deposition, initially in the superior and inferior perilimbal cornea, progressing circumferentially." The band is separated from the limbus by a clear zone (unlike band keratopathy where the clear zone is at the limbus with pathology centrally). The band is wider vertically. In arcus juvenilis (<50 years old): workup for dyslipidaemia (type II hyperlipoproteinaemia, familial hypercholesterolaemia) is mandatory. In patients >50 (arcus senilis): it is a common, benign finding not consistently associated with dyslipidaemia in isolation, though overall cardiovascular risk assessment is prudent. No treatment required.
Q27. Salzmann nodular degeneration (SND) differs from band keratopathy in which key aspects?
- A) SND involves calcium deposition, band keratopathy involves hyaline
- B) SND consists of grey-blue hyaline nodules anterior to Bowman layer occurring after chronic corneal surface disease (trachoma, dry eye, VKC, chronic blepharitis, phlyctenulosis); it is located more centrally/paracentrally (not at interpalpebral band); treated by superficial keratectomy with excellent results
- C) SND is always bilateral and symmetrical
- D) SND responds to topical EDTA chelation
- E) SND is caused by lipid deposition and managed identically to arcus
Answer: B
Rationale: SND: hyaline nodular tissue deposits anterior to Bowman layer, arising in the context of any chronic corneal surface inflammation. It appears as elevated, grey-blue/white nodules, typically paracentrally, that may cause irregular astigmatism and irritation. Unlike band keratopathy (calcium hydroxyapatite in Bowman layer, interpalpebral, responds to EDTA), SND is hyaline in nature and does NOT respond to EDTA. Treatment: superficial keratectomy (manual or excimer PTK) with excellent outcomes. MMC may be applied post-keratectomy to reduce recurrence. The underlying cause (dry eye, VKC, blepharitis) must be controlled to prevent recurrence.
Q28. A 40-year-old woman with chronic inflammatory rheumatoid arthritis develops rapidly progressive peripheral corneal thinning and melting at the 3 o'clock position without infection. The eye is relatively white. What is this condition, and what is the immediate treatment priority?
- A) Bacterial peripheral ulcer; systemic antibiotics
- B) Pellucid marginal degeneration; contact lens fitting
- C) Peripheral ulcerative keratitis (PUK) associated with systemic vasculitis; urgent systemic immunosuppression (oral/IV corticosteroids, cyclophosphamide, or biologics) is required to prevent perforation and treat the underlying vasculitis, which carries high systemic morbidity and mortality
- D) Mooren's ulcer; treat with topical steroids only
- E) Acne rosacea-related PUK; doxycycline
Answer: C
Rationale: Peripheral ulcerative keratitis (PUK) in the context of RA (and other systemic vasculitides: granulomatosis with polyangiitis/Wegener's, polyarteritis nodosa, SLE) represents immune complex deposition in limbal vessels causing necrotizing vasculitis. The "white quiet eye" with progressive peripheral corneal melting is the hallmark. This is an ophthalmic and systemic emergency - PUK in RA is associated with 40% mortality within 5-10 years if underlying disease is not treated, reflecting the severity of systemic vasculitis. Treatment: systemic immunosuppression (pulse IV methylprednisolone, followed by oral prednisolone + immunosuppressive agent). Ocular management: conjunctival resection adjacent to the ulcer (Paton's technique), cyanoacrylate glue for impending perforation, tectonic PKP for perforated cases.
Q29. Mooren's ulcer is a peripheral ulcerative keratitis distinct from PUK associated with systemic disease. Which distinguishing features characterise Mooren's ulcer?
- A) Associated with RA and responds to systemic steroids only
- B) Idiopathic peripheral ulceration with overhanging central edge, no underlying systemic vasculitis, predominantly unilateral in older patients, bilateral in younger patients/Africans; proposed autoimmune mechanism; treated with conjunctival resection, topical cyclosporine, systemic immunosuppression
- C) Typically central corneal, no overhanging edge, responds to antifungals
- D) Caused by bacteria, responds to intensive topical antibiotics
- E) Always bilateral and symmetric, responds to antiviral therapy
Answer: B
Rationale: Mooren's ulcer is characterised by: peripheral corneal ulceration starting at the limbus, progressing circumferentially and centrally with a characteristic overhanging central (stromal) edge undermining the advancing lip; no associated systemic disease (unlike PUK); immune-mediated (possibly molecular mimicry with hepatitis C in some cases). Two clinical types: (1) Unilateral in elderly patients - typically milder, less aggressive; (2) Bilateral in younger patients (particularly African and Asian populations) - more aggressive, more painful. Treatment: conjunctival resection (removing limbal inflammatory cells), topical cyclosporine A, systemic immunosuppression (methotrexate, cyclophosphamide), rituximab for severe refractory cases.
Q30. Terrien marginal degeneration differs from Mooren's ulcer and peripheral ulcerative keratitis in which critical way?
- A) Terrien's is central, the others are peripheral
- B) Terrien's is a non-inflammatory progressive peripheral thinning without ulceration, typically beginning superiorly with lipid deposits at the leading edge of thinning; vascularization is always present; epithelium remains INTACT; it is painless; the major risk is perforation from mild trauma or against-the-rule astigmatism
- C) Terrien's always requires emergency surgery
- D) Terrien's is caused by staphylococcal exotoxins
- E) Terrien's responds to systemic immunosuppression, confirming its autoimmune basis
Answer: B
Rationale: Terrien marginal degeneration is unique among peripheral corneal thinning disorders: it is non-inflammatory (no pain, no active ulceration, no systemic association), the epithelium remains intact over the thinning (unlike Mooren's or PUK where there is an epithelial defect), thinning begins superiorly (not inferiorly like PMD), a lipid line at the central edge of thinning is characteristic, and corneal neovascularization is invariably present. The astigmatism from superior thinning is characteristically against-the-rule. Management: spectacles and contact lenses for optical rehabilitation; surgical tectonic repair (lamellar/crescentic PKP, perilesional keratoplasty) if perforation risk is high or has occurred.
Q31. Neurotrophic keratopathy can result from multiple causes. The recently approved pharmacological treatment targeting the underlying pathophysiology is:
- A) Topical cyclosporine A 0.05% (Restasis)
- B) Topical bevacizumab to reduce neovascularization
- C) Cenegermin-bkbj (Oxervate) - recombinant human nerve growth factor (rhNGF), 20 μg/mL, administered 6x/day for 8 weeks; restores epithelial healing by promoting corneal innervation and epithelial cell survival
- D) Subconjunctival injection of autologous serum
- E) Topical substance P + IGF-1 combination
Answer: C
Rationale: Cenegermin (Oxervate) is a recombinant human nerve growth factor (rhNGF) that is the first and only FDA/EMA-approved treatment specifically for neurotrophic keratopathy (Mackie stages 2 and 3). Mechanism: NGF promotes corneal nerve regeneration, sensory neurotrophism to epithelial cells, and stimulates epithelial proliferation, migration, and differentiation. In the REPARO clinical trials, cenegermin 20 μg/mL (the approved concentration) significantly outperformed vehicle in healing stage 2/3 neurotrophic keratopathy. It is administered 6 times daily for 8 weeks. Other management strategies remain important adjuncts: preservative-free lubricants, therapeutic BCL, punctal occlusion, autologous serum/plasma-rich-in-growth-factors (PRGF), partial/complete tarsorrhaphy, and conjunctival flap.
Q32. In Limbal Stem Cell Deficiency (LSCD), which clinical sign is considered pathognomonic on slit-lamp examination?
- A) Corneal vascularization in any distribution
- B) Inferior pannus only
- C) Conjunctivalization of the cornea - goblet cells invading the corneal surface (detected by impression cytology showing PAS-positive goblet cells on corneal epithelium) and/or irregular, thickened epithelium with superficial vascularization in a "whorled" pattern; corneal epithelium replaced by conjunctival-type epithelium
- D) Subepithelial haze without vascularization
- E) Band keratopathy confined to the limbus
Answer: C
Rationale: LSCD (from chemical burns, Stevens-Johnson syndrome, aniridia, contact lens overwear, mitomycin C toxicity, and others) results in the stem cells of the limbal crypts (palisades of Vogt) being destroyed or depleted. Without limbal stem cells to replenish the corneal epithelium, conjunctival epithelium migrates onto the corneal surface (conjunctivalization). The pathognomonic findings: (1) Irregular, unstable epithelium with superficial vascularization; (2) Impression cytology showing goblet cells (conjunctival marker) on corneal surface - the gold standard diagnostic test; (3) IVCM showing subbasal nerve plexus absence and conjunctival-type cells. Treatment: autologous limbal stem cell transplant (CLAU), living-related conjunctival-limbal allograft (lr-CLAL), cultivated limbal epithelial transplantation (CLET), or simple limbal epithelial transplantation (SLET).
SECTION 5: KERATOPLASTY — ADVANCED SURGICAL & REJECTION (Q33–43)
Q33. In penetrating keratoplasty, the donor button is typically cut 0.25 mm LARGER than the host bed. What is the optical and anatomical rationale?
- A) Larger button prevents wound leak postoperatively
- B) A slightly oversized donor button creates mild overcorrection (myopic shift) offsetting the hyperopic shift from the deep sutures; it also ensures the graft-host junction is slightly offset from the optical zone, improving centration, and promotes a flat graft-host junction under suture tension
- C) Larger button prevents vitreous prolapse
- D) It ensures adequate space for the suture bites to be placed beyond the graft margin
- E) Larger button is needed to ensure adequate endothelial cell count in the periphery
Answer: B
Rationale: Kanski: "The donor button is usually about 0.25 mm larger in diameter than the host site." The rationale: (1) Optical: the larger donor button generates mild central steepening, creating a small myopic shift which partially offsets the hyperopic shift that would otherwise occur from the compressive effect of tight sutures. This is especially relevant in aphakic patients. (2) Anatomical: a slightly oversized button prevents wound gape and promotes apposition at the graft-host junction. In paediatric cases, the donor is often cut the same size or slightly smaller to avoid crowding the angle. Too large (>0.5 mm oversized) risks peripheral anterior synechiae; too small risks high astigmatism.
Q34. During PKP, the order of steps includes preparing the donor BEFORE removing host tissue. What is the critical safety rationale?
- A) The donor must be studied under microscope before use
- B) The donor must be stored at 4°C before use
- C) If a problem is discovered with the donor button after the host cornea has been excised (open-sky eye), there is no spare tissue; preparing the donor first ensures the surgery can be safely abandoned if donor tissue is inadequate, avoiding a catastrophic open-sky situation without viable graft tissue
- D) The donor epithelium takes 30 minutes to stabilise after cutting
- E) The host trephine size must be determined by the donor size, hence donor comes first
Answer: C
Rationale: Kanski: "Preparation of donor cornea should always precede excision of host tissue, in case a problem with the former means that the surgery cannot be completed." This is a fundamental surgical safety principle. An "open sky" (aphakic, vitreous-filled eye after host button excision) with no available donor is an ophthalmological catastrophe - expulsive haemorrhage risk, vitreous prolapse, severe hypotony. By preparing the donor first, the surgeon can identify any issue (inadequate endothelial count, tear in the button, contamination) before committing to the irreversible step of opening the host eye.
Q35. Khodadoust line is the pathognomonic sign of which type of corneal graft rejection?
- A) Epithelial rejection (rejection line at epithelial level)
- B) Subepithelial rejection (Kracher spots)
- C) Endothelial rejection - a linear line of keratic precipitates on the graft endothelium (Khodadoust line) advancing across the graft from the graft-host junction, associated with ciliary injection and a margin of graft oedema behind the KP line
- D) Stromal rejection (diffuse stromal haze)
- E) Descemet membrane rejection (folds in DM with KPs)
Answer: C
Rationale: Kanski: "Endothelial rejection is characterised by a linear pattern of keratic precipitates (Khodadoust line) associated with an area of inflammation at the graft margin." The Khodadoust line represents the advancing front of immunological attack on the donor endothelium - T-lymphocytes migrate from the vascularized host stroma across the graft-host junction destroying donor endothelial cells, leaving a linear swathe of KPs. The area of graft behind the advancing line shows oedema (endothelial failure). This is the most serious form of rejection and requires the most aggressive steroid treatment. Other signs during rejection: epithelial rejection line (average 3 months post-PKP), Kracher spots (subepithelial infiltrates resembling adenoviral SEIs, on donor cornea).
Q36. A male patient receives a corneal graft from a female donor 3 years later. He develops endothelial rejection confirmed by the presence of a Khodadoust line. Which recently identified risk factor for graft rejection and failure does this represent?
- A) ABO blood group mismatch; should screen all donors
- B) Gender incompatibility: Kanski 10e states that "the cornea of a male donor should not be allocated to a female recipient" but a female donor can be used in either male or female recipients; this reflects H-Y antigen (male minor histocompatibility antigen) sensitisation
- C) Cytomegalovirus seropositivity in the donor
- D) Age mismatch between donor (elderly) and recipient (young)
- E) HLA-DR mismatch; complete HLA typing should precede all grafts
Answer: B
Rationale: Kanski 10e (emphasis mine): "Gender incompatibility has recently emerged as an important risk factor for graft rejection and failure. Whereas the cornea of a female donor can be used in either male or female recipients, the cornea of a male donor should not be allocated to a female recipient." This represents a specific male-to-female incompatibility, likely related to the H-Y antigen (encoded on the Y chromosome) acting as a minor histocompatibility antigen. Female recipients sensitised against male-specific H-Y antigen can mount a rejection response. This is an important emerging consideration in corneal donor allocation protocols. The scenario here is actually FEMALE donor → MALE recipient which is acceptable; re-reading: "male donor → female recipient" is the contraindicated combination.
Q37. What is Urrets-Zavalía syndrome, and when does it occur?
- A) Bilateral corneal oedema following cataract surgery
- B) Fixed dilated pupil (permanent mydriasis) occurring as a rare complication of penetrating keratoplasty, typically in keratoconus patients; caused by iris ischaemia from prolonged hypotony or pressure-related anterior segment ischaemia during the open-sky phase of surgery; no effective treatment
- C) Post-keratoplasty endophthalmitis
- D) Retrocorneal membrane formation after DMEK
- E) Persistent epithelial defect in the first week post-PKP
Answer: B
Rationale: Kanski: "A rare complication is a fixed dilated pupil (Urrets-Zavalía syndrome)." It is most classically described after PKP for keratoconus, though it can occur after other anterior segment procedures involving prolonged hypotony. The mechanism is believed to be ischaemia of the iris sphincter and/or ciliary ganglion during the open-sky period or from the use of anticholinergic agents intraoperatively. The pupil becomes permanently fixed and dilated (non-reactive to light or accommodation), causing photophobia and reduced depth of focus. It is notoriously difficult to treat; pilocarpine may provide partial constriction but rarely restores normal function.
Q38. A patient who had PKP 8 years ago presents with gradual painless vision loss. The graft is clear without oedema, IOP is normal, and slit-lamp shows no KPs or AC reaction. Refraction shows 6 D of irregular astigmatism. What is the most likely cause and management?
- A) Graft rejection; intensive topical steroids
- B) Primary graft failure; DMEK
- C) Post-keratoplasty astigmatism (late complication); options: selective suture removal, relaxing incisions, LASIK over the graft (with caution), PRK, toric IOL, rigid/scleral contact lenses
- D) Recurrence of Fuchs dystrophy
- E) Glaucoma causing optic nerve damage; drainage surgery
Answer: C
Rationale: Kanski: "Late complications include astigmatism, recurrence of underlying disease, late wound dehiscence, retrocorneal membrane formation, glaucoma, rejection and failure without rejection." Post-keratoplasty astigmatism (PK-A) is the most common cause of reduced visual acuity after technically successful PKP. Six diopters of irregular astigmatism is common and significantly limits spectacle-corrected VA. Management options: (1) Selective suture removal if sutures still in situ; (2) Corneal topography-guided relaxing incisions (CAIRS - corneal arc-incision refractive surgery); (3) Rigid gas-permeable or scleral contact lenses - often provide best vision; (4) LASIK over graft (with caution - check minimum thickness); (5) PRK/PTK with mitomycin C; (6) Wedge resection for very high astigmatism.
Q39. Regarding DMEK vs. DSAEK: in which clinical scenario is DMEK specifically PREFERRED over DSAEK?
- A) Eyes with a prior failed DSAEK (as the thinner graft prevents confusion with residual DSAEK tissue)
- B) Eyes with combined procedures (phaco-PKP-DMEK) where the phaco step adds risk
- C) Eyes with a primary diagnosis of Fuchs dystrophy, normal anterior segment anatomy, no prior surgery, where optimal visual outcomes (6/6 or better) are the primary goal - DMEK provides the thinnest graft (10-15 μm) with no interface haze, fastest recovery, and best final BCVA
- D) DMEK is always preferred over DSAEK in all scenarios
- E) Eyes with significant peripheral anterior synechiae where DMEK is technically easier to unfold
Answer: C
Rationale: Kanski: "In DMEK only the DM and endothelium are transplanted...the grafts are able to attach to the host tissue with less unevenness, which leads to more rapid visual recovery." DMEK is preferred for Fuchs in a straightforward eye because it provides: thinner graft (10-15 μm vs. 100-150 μm for DSAEK) → no interface scatter → best final BCVA (often 6/6 or better) and fastest visual recovery. DSAEK is preferred when: prior failed DMEK, complex anterior segment (PAS, AC-IOL, tube shunt, prior vitrectomy), eyes where DMEK handling would be extremely difficult, or when surgical expertise in DMEK is limited. The "rebubbling rate" (need for postoperative air injection to reattach graft) is higher for DMEK (~30-40%) vs. DSAEK (~5-10%), which must be balanced against the visual outcome benefits.
Q40. After DSAEK, a patient returns on day 3 with graft detachment confirmed on OCT. The most appropriate immediate management is:
- A) Topical steroids only and recheck in 1 week
- B) Urgent PKP for definitive corneal transplant
- C) Rebubbling - instillation of sterile air or 20% SF6 gas into the anterior chamber via a paracentesis to tamponade and reattach the graft scroll to the host stroma; the patient lies supine for 45-60 minutes
- D) Topical hypertonic saline to dehydrate the graft onto the host
- E) Anti-VEGF injection to reduce oedema
Answer: C
Rationale: Graft detachment after DSAEK/DMEK is a relatively common complication (DMEK ~30-40%, DSAEK ~5-10%). Within the first few days-weeks, rebubbling (anterior chamber air or gas injection) is highly effective at reattaching the graft. The mechanism: air/gas fills the AC, providing upward buoyancy that presses the graft scroll against the host posterior stroma, and the patient's supine position maintains this pressure. Most re-bubbles are successful if performed promptly. After the air dissipates, if the graft remains adherent, the endothelial cells proliferate and seal the interface. Repeated failure of rebubbling may indicate graft roll/fold orientation problems, requiring surgical repositioning or graft replacement.
Q41. The Collaborative Corneal Transplantation Studies (CCTS) examined the role of HLA matching in corneal transplantation. What was its primary finding regarding HLA matching in high-risk corneal transplantation?
- A) HLA matching significantly improved graft survival in all cases
- B) HLA-DR matching provided a statistically significant (but small) benefit in high-risk corneal transplant recipients (those with stromal vascularization); however, the benefit was modest enough that routine HLA matching for all PKPs is not standard practice; ABO compatibility provides minimal additional benefit
- C) Only ABO matching is important; HLA matching has no role in corneal survival
- D) HLA-A and HLA-B matching is more important than HLA-DR matching
- E) HLA matching is only relevant in paediatric keratoplasty
Answer: B
Rationale: Kanski: "Human leukocyte antigen (HLA) matching has a small beneficial effect on graft survival." The CCTS found that in high-risk patients (those with stromal neovascularization, the primary risk factor for rejection), HLA-DR matching provided statistically significant improvement in graft survival, but the benefit was modest. Due to practical limitations (small donor pool, need for urgent transplantation), routine HLA matching for all PKPs is not standard. It is generally reserved for high-risk patients (multiple prior graft failures, highly vascularised corneas, young patients requiring long-term survival). ABO compatibility is generally performed as a precaution though the cornea has limited blood group antigen expression.
Q42. What is the clinical significance of loose or broken sutures after PKP, and what is the immediate action?
- A) Loose sutures are cosmetically bothersome only; they can be removed electively at routine follow-up
- B) Broken/loose sutures act as a scaffold for corneal vascularization into the graft, which significantly increases the risk of graft rejection; Kanski: "Removal of broken or loose individual sutures should be performed as soon as identified" to prevent localized vascularization; also risk of suture-related infectious keratitis
- C) Loose sutures are a sign of graft rejection and require immediate steroid treatment
- D) Sutures should never be removed before 18 months post-PKP regardless of clinical status
- E) Suture-related problems are only significant in the first month post-PKP
Answer: B
Rationale: Kanski: "Removal of broken or loose individual sutures should be performed as soon as identified, as this reduces the risk of localized vascularization and graft rejection." A loose suture creates a conduit for blood vessel ingrowth from the peripheral vascular limbus into the graft-host junction and potentially the graft. Vascularization is the most important risk factor for rejection (it allows antigen-presenting cells and effector T-cells to access the graft). Additionally: loose sutures can harbour bacteria, especially Streptococcal crystalline keratopathy post-PKP on steroids. Kanski also notes: "A protruding suture (risk of infection) causes marked sterile reaction and papillary hypertrophy."
Q43. Following PKP, a patient on topical prednisolone 1% four times daily develops elevated IOP of 35 mmHg at 6 months post-op. What are the contributing factors and how should IOP be measured?
- A) The elevated IOP is always from graft rejection; add systemic steroids
- B) Steroid-induced ocular hypertension is common post-PKP and contributes to open-angle IOP rise; early post-PKP IOP measurement: avoid applanation tonometry on the graft - use non-contact/air-puff tonometry, Tono-Pen, or Schiotz as applanation readings are unreliable due to variable graft curvature/thickness. Management: reduce steroid frequency, add IOP-lowering drops (beta-blocker, prostaglandin analogue with caution), avoid pilocarpine
- C) The elevated IOP confirms angle closure; perform urgent laser iridotomy
- D) IOP elevation post-PKP is always from peripheral anterior synechiae
- E) Applanation tonometry on the graft gives the most accurate readings
Answer: B
Rationale: Kanski: "Monitoring of IOP: Applanation tonometry is relatively unreliable so measurement is commonly performed during the early postoperative period with a non-applanation method." Post-PKP IOP elevation causes: (1) Steroid response (most common); (2) Peripheral anterior synechiae (from large graft >8 mm, flat AC, or endophthalmitis); (3) Pre-existing glaucoma exacerbated by steroid. Uncontrolled IOP post-PKP leads to progressive endothelial cell loss and eventual graft failure. Management: step down steroids to minimum effective level (never stop abruptly - rejection risk); add IOP-lowering medication. Carbonic anhydrase inhibitors are generally avoided long-term as they may reduce endothelial function. Tube shunt surgery may be needed for uncontrolled glaucoma post-PKP.
SECTION 6: HZO, VZV KERATITIS & MISCELLANEOUS (Q44–50)
Q44. Hutchinson's sign in Herpes Zoster Ophthalmicus (HZO) describes vesicles at the tip/root/side of the nose. Which statement about its clinical significance is CURRENT (per Kanski 10e)?
- A) Hutchinson's sign is 100% predictive of ocular involvement and mandates urgent ophthalmological referral
- B) Contrary to previous teaching, Hutchinson's sign may not be predictive of ocular involvement, as both false-positive and false-negative findings are common; however, a rash in the distribution of the supratrochlear nerve (lower forehead) IS predictive of ocular involvement
- C) Hutchinson's sign only occurs in immunocompromised patients
- D) Hutchinson's sign indicates imminent corneal perforation
- E) A negative Hutchinson's sign (tip of nose unaffected) completely excludes ocular involvement
Answer: B
Rationale: Kanski 10e: "Hutchinson sign describes vesicles in the skin supplied by the external nasal nerve...Contrary to previous teaching, Hutchinson's sign may not be predictive of ocular involvement, as both false-positive and false-negative findings are common. However, a rash in the distribution of the supratrochlear nerve (lower part of the forehead) is predictive." This is an important update from the traditional teaching that Hutchinson's sign reliably predicts ocular involvement. All HZO patients (V1 dermatome) should receive ophthalmological assessment regardless of Hutchinson's sign status, because: corneal anaesthesia, disciform keratitis, uveitis, secondary glaucoma, and optic neuritis can all occur independent of the nasal tip involvement.
Q45. HZO treatment: A 65-year-old presents with 2-day history of right V1 dermatomal rash. For corneal involvement in HZO, which antiviral regimen is recommended, and what is the optimal treatment window?
- A) Topical acyclovir only; no systemic treatment needed
- B) Oral antiviral within 72 hours of rash onset: valacyclovir 1 g TDS for 7 days (or acyclovir 800 mg 5x/day for 7 days, or famciclovir 500 mg TDS for 7 days); started within 72 hours to reduce viral replication, severity of acute neuritis, and risk of post-herpetic neuralgia; may be extended beyond 72 hours in immunocompromised patients or if new lesions are still appearing
- C) IV acyclovir for all HZO cases
- D) Antiviral treatment has no effect on HZO corneal complications
- E) Treatment should be withheld until ocular involvement is confirmed
Answer: B
Rationale: HZO antiviral treatment within 72 hours of rash onset significantly reduces: duration and severity of acute neuritis, risk of post-herpetic neuralgia (PHN), risk of ocular complications. Oral valacyclovir 1 g TDS is the preferred regimen (better bioavailability than acyclovir, equivalent to IV acyclovir at standard doses). IV acyclovir is reserved for immunocompromised patients, disseminated zoster, or CNS involvement. The 72-hour window is not absolute - treatment beyond 72 hours still provides benefit in active disease (new lesions still forming). All patients with V1 HZO need ophthalmological review. For established corneal complications: HZO disciform/interstitial keratitis treated with topical steroids + prophylactic antiviral (same as HSV stromal keratitis principles).
Q46. Interstitial keratitis (IK): A 20-year-old presents with bilateral deep stromal vascularization, "salmon patch" corneal lesions, and anterior uveitis. She has a history of childhood infections. Serology shows positive VDRL and FTA-ABS. What is the diagnosis, mechanism, and treatment?
- A) Cogan syndrome; autoimmune; systemic steroids + hearing assessment
- B) Congenital syphilis interstitial keratitis caused by immune reaction to Treponema pallidum antigens (not active infection) in the corneal stroma; "salmon patch" = deep stromal vascularization; treated with systemic penicillin (to treat active syphilis if present) plus topical and systemic steroids to suppress the immune stromal reaction; "ghost vessels" remain permanently in healed IK
- C) Tuberculosis IK; anti-TB therapy
- D) HSV stromal keratitis; topical acyclovir + steroids
- E) Cogan syndrome; IV steroids only, no antibiotic needed
Answer: B
Rationale: IK from congenital syphilis (most common historical cause) presents in the second decade as an immune reaction to spirochetal antigens deposited in the stroma during fetal infection. The active treponemas may be absent at the time of IK (hence the immune, not infectious, mechanism). Classic findings: deep stromal vascularization appearing as the "salmon patch" (active engorged vessels) → eventually vessel regression leaving "ghost vessels" (empty vascular channels visible on slit-lamp or FA). VDRL + FTA-ABS positivity confirms syphilitic aetiology. Treatment: IV/IM penicillin for active syphilis (even if IK mechanism is immune, active infection must be treated) + topical steroids for the IK itself + cycloplegia. Cogan syndrome is non-syphilitic IK (negative serology) with sensorineural hearing loss/vestibular dysfunction, treated with systemic steroids.
Q47. Neurotrophic keratopathy staging: A patient with longstanding diabetic corneal neuropathy presents with a painless oval epithelial defect centrally with rolled edges, no stromal infiltrate, and stromal haze. This represents which Mackie stage, and what is the risk if untreated?
- A) Mackie Stage 1 (epithelial irregularity); risk of superficial punctate keratitis
- B) Mackie Stage 2 (persistent epithelial defect with rolled/heaped edges); if untreated progresses to Stage 3 (stromal ulceration with risk of corneal perforation and endophthalmitis); diabetes is a common non-herpetic cause of neurotrophic keratopathy
- C) Mackie Stage 3 (stromal ulceration); emergency surgery indicated
- D) Mackie Stage 1; treat with lubricants and discharge
- E) This represents bullous keratopathy, not neurotrophic keratopathy
Answer: B
Rationale: The Mackie classification: Stage 1 = epithelial irregularity (increased epithelial permeability, reduced corneal reflex, irregular fluorescein staining, filaments, punctate epithelial erosions); Stage 2 = persistent epithelial defect (PED) - non-healing epithelial defect with characteristic smooth, rolled, heaped-up margins (the surrounding epithelium piles up at the defect edge because there is no innervation-driven motility signal to close it); Stage 3 = stromal ulceration, melting, perforation risk. The cardinal feature of neurotrophic keratopathy at all stages: absence or markedly reduced corneal sensation on Cochet-Bonnet aesthesiometry. Causes beyond HSV/HZO: diabetes, multiple sclerosis, acoustic neuroma surgery, Riley-Day syndrome, contact lens overwear, topical anaesthetic abuse.
Q48. A 35-year-old soft contact lens wearer removes his lenses for 2 weeks and is found to have inferior corneal vascularization, limbal hyperaemia, and 2 mm pannus. His BCVA is 6/6. What is the most likely diagnosis and the clinical significance?
- A) Keratoconus; urgent CXL needed
- B) Contact lens-induced peripheral ulcerative keratitis (CLPU) or contact lens-induced corneal vascularization from chronic hypoxia; corneal neovascularization in response to chronic hypoxia (low Dk/t silicone hydrogel lenses, extended wear, or poor hygiene); new vessels represent potential antigen-presenting cell highways that could complicate future corneal surgery
- C) Fuchs dystrophy; DMEK required
- D) Acanthamoeba keratitis at an early stage
- E) Epidemic keratoconjunctivitis; self-limiting
Answer: B
Rationale: Corneal neovascularization from contact lens hypoxia occurs when lenses with insufficient oxygen transmissibility (Dk/t) are worn, particularly in extended/overnight modalities. The corneal periphery develops new vessels from limbal arcades (most commonly superiorly and inferiorly - the "4-and-8 o'clock" pattern in soft lens wearers). The vessels grow into the cornea - 2 mm of vessel growth is considered a threshold requiring refitting or lens discontinuation. Clinical significance: (1) Aesthetically concerning; (2) The neovascularization introduces antigen-presenting cells (APCs) and lymphocytes into the normally immune-privileged cornea, dramatically increasing graft rejection risk if this patient ever needs keratoplasty; (3) If vessels reach the visual axis, vision is affected. Management: fit higher-Dk lenses, reduce wearing time, daily disposable lenses; topical steroids for active lipid deposition.
Q49. A 45-year-old pharmacist presents with bilateral diffuse epithelial toxicity with PEK, conjunctival chemosis, and surface irregularity after starting a new topical glaucoma regimen. What is the most likely culprit and mechanism?
- A) The active drug (timolol) directly toxic to the epithelium
- B) Benzalkonium chloride (BAK) - the preservative in multi-dose topical eye drops; BAK is a detergent cationic surfactant that disrupts the corneal epithelial tight junctions and lipid layer, causes mitochondrial damage and apoptosis of epithelial and goblet cells, reduces mucin expression, and exacerbates dry eye; switching to preservative-free formulations resolves the toxicity
- C) Hypersensitivity to the prostaglandin analogue
- D) The pH of the drop formulation causing acid burn
- E) Allergic conjunctivitis from the packaging material
Answer: B
Rationale: Benzalkonium chloride (BAK) is the most commonly used preservative in multi-dose ophthalmic preparations and the most common cause of ocular surface toxicity in chronic glaucoma patients on multiple drops. BAK: (1) disrupts tear film lipid layer; (2) directly cytotoxic to epithelial cells; (3) reduces goblet cell density; (4) causes conjunctival squamous metaplasia; (5) accumulates in corneal and conjunctival tissues with chronic use. The toxicity is dose-dependent and cumulative. Patients on multiple preserved drops (common in glaucoma) are at highest risk. Management: switch to preservative-free (PF) formulations where available; use preservative-free artificial tears; fixed-combination drops reduce the number of drop instillations. This is increasingly important as many glaucoma patients need long-term multi-drug therapy.
Q50. A 28-year-old woman with a 3-year history of seasonal allergic eye disease presents with a superior corneal shield ulcer (Togby ulcer), a Trantas dot at the limbus, and giant papillae on the upper tarsal conjunctiva. She rubs her eyes frequently. What is this condition, the mechanism of the shield ulcer, and its management priority?
- A) Epidemic keratoconjunctivitis; topical antiviral
- B) Atopic keratoconjunctivitis; systemic tacrolimus
- C) Vernal keratoconjunctivitis (VKC) - the shield ulcer (sterile, oval, superior, superficial punctate epithelial erosion/ulcer under giant papillae) results from mechanical trauma by giant papillae on the superior tarsal plate abrading the superior corneal epithelium + toxic effect of eosinophil products (MBP - major basic protein, ECP) on the epithelium; Trantas dots = limbal eosinophil/lymphocyte aggregates. Management: stop eye rubbing (most critical); topical mast cell stabiliser/antihistamine (olopatadine, ketotifen, nedocromil); topical cyclosporine A for moderate/severe cases; supratarsal triamcinolone injection for severe papillae; shield ulcers treated with bandage CL, topical steroids, and fibronectin drops; keratoplasty for corneal scarring (high rejection risk - prefer DALK)
- D) Giant papillary conjunctivitis from contact lens; discontinue CL
- E) Ligneous conjunctivitis; systemic ciclosporin
Answer: C
Rationale: VKC is a bilateral, recurrent, chronic allergic conjunctivitis predominantly affecting young males in warm climates. The shield ulcer (Buckley type III VKC involvement) is the most serious corneal complication, caused by mechanical abrasion from giant cobblestone papillae (>1 mm) on the upper tarsal plate repeatedly traumatising the superior corneal epithelium, combined with eosinophil granule protein toxicity. Trantas dots (limbal white spots = limbal papillae with eosinophils and lymphocytes) are pathognomonic of VKC. Kanski: VKC and atopic keratoconjunctivitis both carry increased risk of graft rejection - DALK is preferred over PKP when corneal surgery is needed. Eye rubbing in VKC is also associated with keratoconus development - CXL should be performed if KC progression is documented.
Summary Answer Key
| Q | Topic | Ans | Q | Topic | Ans | |
|---|---|---|---|---|---|---|
| 1 | Corneal thickness - stroma | C | 26 | Arcus senilis | B | |
| 2 | Endothelial pump / min ECD | D | 27 | Salzmann vs band keratopathy | B | |
| 3 | Corneal transparency mechanism | B | 28 | PUK - systemic vasculitis | C | |
| 4 | PMD topography "crab-claw" | B | 29 | Mooren's ulcer features | B | |
| 5 | Subclinical KC screening | B | 30 | Terrien marginal degeneration | B | |
| 6 | Moderate KC - CXL | B | 31 | Cenegermin (NGF) | C | |
| 7 | Hydrops history - DALK contraindicated | B | 32 | LSCD - goblet cells | C | |
| 8 | DALK vs PKP advantages | B | 33 | PKP donor button size | B | |
| 9 | DALK for KC with scar | B | 34 | Donor before host tissue - safety | C | |
| 10 | PMD - no Fleischer/Vogt | C | 35 | Khodadoust line | C | |
| 11 | Keratoglobus vs KC | B | 36 | Gender incompatibility | B | |
| 12 | CXL 400 μm threshold | B | 37 | Urrets-Zavalía syndrome | B | |
| 13 | Acanthamoeba - calcofluor white | B | 38 | Post-PKP astigmatism | C | |
| 14 | Acanthamoeba treatment - PHMB | B | 39 | DMEK preferred scenario | C | |
| 15 | Fungal keratitis - natamycin | B | 40 | DSAEK detachment - rebubble | C | |
| 16 | Candida vs filamentous fungi | B | 41 | CCTS / HLA matching | B | |
| 17 | HSV dendrite vs Acanthamoeba | C | 42 | Loose sutures - remove immediately | B | |
| 18 | HSV stromal keratitis treatment | B | 43 | IOP monitoring post-PKP | B | |
| 19 | HEDS trial - oral acyclovir | B | 44 | Hutchinson's sign | B | |
| 20 | Neurotrophic keratopathy - HZO | C | 45 | HZO antiviral timing | B | |
| 21 | Bacterial keratitis - fluoroquinolone | B | 46 | Syphilitic IK | B | |
| 22 | Crystalline keratopathy - Strep viridans | B | 47 | Mackie Stage 2 | B | |
| 23 | Microsporidial keratitis - two forms | A | 48 | CL-induced neovascularization | B | |
| 24 | Thygeson SPK | B | 49 | BAK toxicity | B | |
| 25 | Band keratopathy - metabolic causes | B | 50 | VKC - shield ulcer | C |
Sources: Kanski's Clinical Ophthalmology 10e (Chapters 7-8); Wills Eye Manual 8e (Chapters 4.8-4.27)
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