1000138293.jpg
1000138291.jpg
Answer all the questions
I'll read the medical library skill first, then answer all questions from this ophthalmology exam paper.
Reading File
Now let me search the library for all the key topics in parallel.
Finding Sources
Finding Sources
Finding Sources
Finding Sources
Now let me read the key ophthalmology sections in parallel:
Reading File
Reading File
Reading File
Reading File
Good. Now let me read the cataract section from Kanski's and the pterygium management section, plus more on the short note topics:
Reading File
Reading File
Finding Sources
Finding Sources
Now let me read the cataract management section and subconjunctival haemorrhage from Kanski's, plus myopia from Goldman-Cecil:
Reading File
Reading File
Reading File
I now have enough textbook material to write comprehensive answers. Let me also read a bit more on chalazion and the cataract surgery/investigation section:
Reading File
Reading File
I now have sufficient material from the textbooks. Let me compile all the answers:---
Graphic Era Institute of Medical Sciences - Ophthalmology Exam Answers
SECTION A (50 Marks)
Q1. CATARACT (Long Answer - 10 Marks)
a) Define Cataract (1 mark)
A cataract is any opacification of the crystalline lens of the eye. The term comes from the Greek word for "waterfall," reflecting the appearance of a white opacity in the pupil. It is the leading cause of reversible blindness worldwide. (Goldman-Cecil Medicine, p. 4131; Kanski's Clinical Ophthalmology)
b) Etiology and Classification of Cataract (3 marks)
Etiology
| Category | Causes |
|---|---|
| Age-related (senile) | Most common; due to protein aggregation, oxidative damage, UV radiation |
| Congenital | Rubella, galactosaemia, Down syndrome, Lowe syndrome, hereditary |
| Traumatic | Blunt or penetrating ocular injury, electric injury, radiation |
| Metabolic | Diabetes mellitus (sorbitol accumulation), hypocalcaemia, Wilson disease |
| Drug-induced | Long-term corticosteroids (posterior subcapsular), phenothiazines, chlorpromazine |
| Secondary (complicated) | Uveitis, high myopia, retinitis pigmentosa, intraocular tumours |
| Radiation | X-rays, infrared (glass-blower's cataract), microwave |
| Iatrogenic | Post-vitrectomy, silicone oil (almost all phakic eyes with silicone oil develop cataract), intravitreal gas |
Classification
1. By age of onset:
- Congenital cataract (present at or shortly after birth)
- Acquired (developmental, senile, traumatic, etc.)
2. By morphology (location of opacity) - Senile types:
- Nuclear (Nuclear sclerotic) cataract - exaggeration of normal aging; yellowish-brown hue due to urochrome deposition; associated with myopia ("second sight of the aged")
- Cortical cataract - clefts and vacuoles in cortex; cuneiform (wedge-shaped) or radial spoke-like opacities; starts infero-nasally; common cause of glare
- Posterior subcapsular (PSC) cataract - lies just anterior to posterior capsule; granular/plaque-like; most visually disabling (at nodal point of eye); worse in bright light and near work; associated with corticosteroids
- Anterior subcapsular cataract - fibrous metaplasia of lens epithelium
3. By maturity (degree of opacification):
- Immature - lens partially opaque; some cortex clear
- Mature - lens completely opaque; no red reflex
- Hypermature - shrunken, wrinkled anterior capsule due to leakage of water
- Morgagnian - hypermature cataract with liquefied cortex; nucleus sinks inferiorly (Kanski's Clinical Ophthalmology, p. 323)
c) Signs and Symptoms of a Patient with Senile Cataract (3 marks)
Symptoms:
- Painless, progressive diminution of vision - the cardinal symptom
- Glare - especially with cortical and PSC cataracts; difficulty driving at night due to oncoming headlights
- Monocular diplopia - due to irregular refraction through different zones of the lens
- Frequent change of glasses - due to progressive refractive change
- "Second sight" in nuclear cataract - patient temporarily regains near vision without spectacles (increased refractive index of nucleus causes myopic shift)
- Reduced contrast sensitivity - difficulty in dim illumination
- Colour desaturation - colours appear yellowed or washed out
Signs on Examination:
- Reduced visual acuity on Snellen chart testing
- Absent or diminished red reflex on distant direct ophthalmoscopy (replaced by dark spokes or opacities)
- Slit-lamp biomicroscopy - identifies type, location, density of opacity
- PSC: black vacuolated appearance on retroillumination
- Nuclear: yellowish-brown lens nucleus with oblique illumination
- Cortical: cuneiform spokes in oblique illumination
- Shadows on retroillumination corresponding to the type of cataract
- Shafer's sign (iridescent spots) in cortical cataract
d) Investigations and Management of Cataract (3 marks)
Investigations
Pre-operative work-up:
- Visual acuity - Snellen chart (distance) and near vision chart
- Refraction - objective and subjective
- Slit-lamp examination - confirm cataract type, anterior segment assessment
- Intraocular pressure (IOP) measurement - tonometry to rule out glaucoma
- Pupil dilation and fundus examination - to assess posterior segment (retina, optic disc) and predict visual outcome
- Biometry (A-scan ultrasonography) - to measure axial length for IOL power calculation
- Keratometry - to measure corneal curvature for IOL calculation
- B-scan ultrasound - when fundus not visible due to dense cataract
- Specular microscopy - to assess endothelial cell count
- Potential acuity meter (PAM) / laser interferometry - to estimate potential vision through a dense cataract
- Systemic workup: Blood sugar, blood pressure, coagulation profile, ECG, chest X-ray before surgery
Management
Medical (no proven medical treatment to reverse cataract):
- Lifestyle modifications: UV-blocking sunglasses, smoking cessation
- Optimise refractive correction temporarily while awaiting surgery
- Control underlying causes (e.g., blood sugar in diabetes)
Surgical - Definitive treatment:
Surgery is indicated when:
- Cataract significantly impairs the patient's lifestyle/daily activities
- Mature/hypermature cataract (risk of phacolytic glaucoma, lens-induced uveitis)
- Cataract causing secondary complications
Methods:
| Method | Description |
|---|---|
| Phacoemulsification (Phaco) | Gold standard; ultrasonic probe emulsifies nucleus through small incision (2.2-3 mm); intraocular lens (IOL) implanted; rapid recovery |
| Small Incision Cataract Surgery (SICS) | Manual; 5-7 mm incision; good for hard nuclei; cost-effective |
| Extra-capsular cataract extraction (ECCE) | Nucleus expressed intact through larger incision |
| Intra-capsular cataract extraction (ICCE) | Entire lens with capsule removed; largely obsolete |
Intraocular Lens (IOL):
- Synthetic IOL implanted in the posterior chamber (in-the-bag)
- Power calculated by biometry (SRK II / SRK-T formula)
- Monofocal, multifocal, toric (for astigmatism), or accommodating IOLs available
Post-operative care:
- Topical antibiotics + steroid drops
- Watch for complications: posterior capsular opacification (PCO) - treated by Nd:YAG laser capsulotomy, endophthalmitis, cystoid macular oedema
(Goldman-Cecil Medicine, p. 4131; Kanski's Clinical Ophthalmology)
Short Notes - Section A (8 × 5 = 40 Marks)
2. Night Blindness (Nyctalopia)
Definition: Difficulty or inability to see in dim light or darkness, with relatively normal vision in daylight. The term nyctalopia (from Greek "night" + "blind") denotes reduced dark adaptation.
Pathophysiology: Vision in dim light depends on rod photoreceptors which contain rhodopsin (visual purple), a photopigment requiring Vitamin A (11-cis retinol) for regeneration. Any process impairing rods or rhodopsin causes night blindness.
Causes:
- Vitamin A deficiency - most common cause worldwide; rhodopsin cannot be regenerated; also causes Bitot's spots and xerophthalmia
- Retinitis pigmentosa - progressive rod-cone dystrophy; classic triad: night blindness, bone-spicule pigmentation, tunnel vision
- Congenital stationary night blindness (CSNB) - non-progressive hereditary condition
- Advanced glaucoma / optic atrophy
- Choroideremia - X-linked; progressive choroidal atrophy
- Gyrate atrophy - ornithine aminotransferase deficiency
- After pan-retinal photocoagulation (PRP)
- Drugs: phenothiazines, chloroquine, quinine
- Refractive errors - especially undercorrected myopia
- Miosis (pharmacologic or pathologic) - reduces light reaching retina
Clinical features:
- Difficulty driving at night
- Bumping into objects in dim light
- Prolonged dark adaptation time
- Associated features depend on cause (e.g., visual field constriction in RP)
Investigations: Dark adaptometry, electroretinogram (ERG - reduced rod response), serum Vitamin A levels, fundus examination
Management:
- Vitamin A supplementation (if deficiency)
- Treat underlying cause
- Genetic counselling for hereditary forms (Wills Eye Manual; Kanski's Clinical Ophthalmology)
3. Red Eye
Definition: A non-specific finding of conjunctival or ciliary injection indicating inflammation or irritation of the ocular or adnexal structures.
Differential Diagnosis - Common Causes:
| Feature | Acute Conjunctivitis | Acute Iridocyclitis | Acute Angle-Closure Glaucoma | Corneal Ulcer |
|---|---|---|---|---|
| Pain | Mild/grittiness | Moderate | Severe (+ nausea) | Severe |
| Vision | Normal | Mildly reduced | Markedly reduced | Varies |
| Discharge | Profuse (bacterial) watery (viral) | None/lacrimation | None | Purulent |
| Cornea | Clear | Keratic precipitates | Hazy (oedematous) | Ulcer present |
| Pupil | Normal | Small, irregular | Mid-dilated, fixed | Normal |
| IOP | Normal | Normal/low | Very high | Normal |
| Injection type | Conjunctival (peripheral) | Ciliary/circumcorneal | Mixed | Circumcorneal |
Adnexal causes: Trichiasis, entropion, blepharitis, meibomitis, dacryocystitis, floppy eyelid syndrome
Approach: Detailed history (onset, discharge, pain, vision change, trauma, contact lens use), slit-lamp examination, IOP, and fluorescein staining are key.
4. Chalazion
Definition: A chalazion is a chronic, sterile, lipogranulomatous inflammation of a meibomian (tarsal) gland resulting from obstruction and retention of its lipid secretion (meibum), which acts as a foreign body stimulus.
Pathology: Blocked meibomian gland duct -> retained lipid-rich sebum -> foreign body granulomatous reaction with lymphocytes, plasma cells, and epithelioid cells. Histology shows lipogranuloma.
Distinguishing from Hordeolum (Stye):
| Feature | Chalazion | Hordeolum (stye) |
|---|---|---|
| Type | Chronic, sterile granuloma | Acute bacterial abscess |
| Pain | Painless (or mildly tender) | Painful |
| Gland | Meibomian (deep) | Zeiss/Moll (external); Meibomian (internal) |
| Location | Within tarsus, non-mobile | At lid margin |
| Resolution | Weeks-months | Days with treatment |
Clinical features:
- Non-mobile, painless nodule in the eyelid (usually upper)
- May point onto conjunctival surface (appears as red velvety granulation tissue)
- May grow large enough to press on cornea and induce astigmatism
- Recurrent chalazion at the same site should raise suspicion for sebaceous gland carcinoma
Management:
- Conservative: Warm compresses 3-4 times daily, gentle lid massage (most resolve spontaneously over weeks)
- Intralesional injection: Triamcinolone acetonide (0.1-0.2 mL) - effective for persistent lesions
- Surgical incision and curettage (I&C): Under local anaesthesia; vertical incision on conjunctival surface; contents curetted - for persistent chalazia not responding to above
- Recurrent/atypical lesions: Biopsy to exclude sebaceous carcinoma (Goldman-Cecil Medicine, p. 4128)
5. Subconjunctival Haemorrhage
Definition: Bleeding between the conjunctiva and the underlying episclera/sclera, appearing as a well-defined, bright red patch on the white of the eye (sclera). No blood is found in the anterior chamber.
Aetiology:
| Category | Examples |
|---|---|
| Idiopathic/spontaneous | Most common; especially in elderly |
| Trauma | Blunt or penetrating trauma, eye rubbing, contact lens use |
| Raised venous pressure | Coughing, sneezing, vomiting, straining (Valsalva), strangulation |
| Hypertension | Should be excluded in recurrent cases |
| Blood dyscrasias | Anticoagulants (warfarin, aspirin), thrombocytopenia, haemophilia, leukaemia |
| Ocular surgery | Post-operative (very common) |
| Infections | Viral or bacterial conjunctivitis |
| Systemic | Diabetes mellitus |
Clinical features:
- Sudden onset of a painless, bright-red patch on the conjunctiva
- Well-demarcated; does not cross limbus
- Usually unilateral
- Patient may feel a momentary sharp pain or "popping" sensation at onset
- Vision is not affected
- No discharge; cornea clear; normal IOP
Investigations (if recurrent or bilateral):
- Blood pressure measurement
- Full blood count (FBC), coagulation screen (PT/INR)
- Blood glucose
Management:
- Reassurance - almost always self-limiting; resolves in 1-3 weeks (gradually changes colour: bright red -> orange -> yellow, like a bruise)
- Artificial tears for mild irritation
- Cold compresses in first 24 hours, warm compresses thereafter
- Treat the underlying cause (e.g., control blood pressure)
- Avoid aspirin/NSAIDs unless medically essential (Kanski's Clinical Ophthalmology, p. 218)
6. Myopia (Short-sightedness / Nearsightedness)
Definition: Myopia is a refractive error in which parallel rays of light from a distant object are focused in front of the retina (instead of on it) when the eye is at rest (no accommodation). The far point is at a finite distance in front of the eye.
Types:
- Simple (school myopia) - axial length increase; most common; begins in childhood
- Pathologic (degenerative/malignant myopia) - progressive; axial length >25 mm (can reach 40 mm); severe structural complications
- Curvature myopia - excess corneal/lens curvature
- Index myopia - increased refractive index of lens (e.g., nuclear cataract, diabetes)
Aetiology:
- Axial - most common cause; eyeball is too long
- Genetic predisposition - strong family history; associated with Marfan, Stickler, Cornelia de Lange syndromes
- Environmental factors: prolonged near work
- Associated with: Prematurity, Down syndrome
Clinical Features:
- Symptoms: Blurred distance vision; clear near vision; squinting to see distant objects; eye fatigue; headache
- Signs: Refractive error measured in negative (-) dioptres on retinoscopy/autorefractometry; fundus in pathologic myopia shows: tilted disc, myopic crescent (peripapillary atrophy), posterior staphyloma, lattice degeneration, tessellated fundus
Complications of Pathologic Myopia:
- Retinal holes and detachment
- Choroidal neovascularisation (CNV) - Fuchs spot (dark pigmented scar)
- Posterior staphyloma
- Vitreous liquefaction and floaters
- Open-angle glaucoma (increased risk)
- Macular degeneration
Management:
- Optical correction: Concave (diverging) lenses (glasses or contact lenses)
- Refractive surgery: LASIK, PRK, SMILE (corneal refractive procedures for stable myopia)
- Myopia control (children): Atropine drops (0.01-0.1%), orthokeratology contact lenses, multifocal lenses
- Pathologic myopia complications: Anti-VEGF injections for CNV; laser treatment for retinal breaks (Goldman-Cecil Medicine, p. 4120-4121)
7. Acute Conjunctivitis
Definition: Acute inflammation of the conjunctiva (mucous membrane lining the inner eyelid and front of the eye), characterized by conjunctival injection, discharge, and foreign body sensation, of sudden onset.
Classification and Aetiology:
| Type | Common Organisms/Causes | Discharge |
|---|---|---|
| Bacterial | S. aureus, S. pneumoniae, H. influenzae, Moraxella | Mucopurulent, profuse |
| Gonococcal | Neisseria gonorrhoeae | Hyperpurulent ("pus pouring out") - ophthalmia neonatorum |
| Viral | Adenovirus (most common), EBV, HSV, enterovirus | Watery, serous |
| Chlamydial | Chlamydia trachomatis (trachoma, inclusion conjunctivitis) | Mucopurulent, chronic |
| Allergic | Pollen, animal dander, contact lens solutions | Watery + mucoid strings; intense itching |
Clinical Features:
- Symptoms: Red eye, foreign body sensation ("gritty, sand-in-eye" feeling), discharge causing lids to stick together in the morning, lacrimation, mild photophobia
- Signs: Conjunctival injection (more peripherally), papillae or follicles on tarsal conjunctiva, discharge, chemosis (conjunctival oedema)
- Vision usually normal; cornea usually clear; pupils normal
Investigations:
- Conjunctival swab for Gram stain and culture/sensitivity
- Giemsa stain for chlamydial inclusions
Management:
Bacterial:
- Topical antibiotic drops: Chloramphenicol 0.5%, ciprofloxacin 0.3%, moxifloxacin q.i.d. for 5-7 days
- Hygiene: hand washing, avoid sharing towels
Viral:
- Self-limiting (1-2 weeks)
- Supportive: cold compresses, lubricant drops
- Topical antivirals if HSV (aciclovir 3% ointment)
Allergic:
- Topical antihistamines (e.g., olopatadine), mast cell stabilisers (e.g., sodium cromoglicate)
- Cold compresses, oral antihistamines
- Avoid allergen
Gonococcal (emergency):
- IV/IM ceftriaxone + saline irrigation
8. Keratitis
Definition: Inflammation of the cornea, characterized by corneal ulceration or infiltration, pain, photophobia, and reduction in visual acuity. It is an ophthalmic emergency.
Classification:
1. Infective Keratitis:
| Type | Causative Agents | Key Features |
|---|---|---|
| Bacterial | Pseudomonas aeruginosa (contact lenses), S. aureus, S. pneumoniae, Moraxella | Rapid progression; grey-white ulcer with suppuration |
| Viral | Herpes simplex virus (HSV) - most common viral cause | Dendritic ulcer (pathognomonic); recurrent; reduced corneal sensation |
| Fungal | Aspergillus, Fusarium (vegetative trauma), Candida (immunocompromised) | Dry, feathery margins; satellite lesions; slower course |
| Acanthamoeba | Acanthamoeba spp. (contact lens + contaminated water) | Severe pain disproportionate to signs; ring infiltrate; perineural infiltrates |
2. Non-infective Keratitis:
- Exposure keratitis (lagophthalmos)
- Neurotrophic keratitis (reduced corneal sensation)
- UV keratitis ("welder's flash," snow blindness)
- Autoimmune (Mooren's ulcer, Terrien's marginal degeneration)
Symptoms:
- Severe pain, photophobia, lacrimation (epiphora)
- Blepharospasm
- Blurred vision
- Mucopurulent discharge
Signs:
- Corneal infiltrate or ulcer (fluorescein stains positive - green under cobalt blue light)
- Ciliary/circumcorneal injection
- Hypopyon (pus in anterior chamber) - indicates severe bacterial or fungal infection
- Reduced corneal transparency
- Reduced corneal sensation (HSV, Acanthamoeba)
Investigations:
- Corneal scraping for Gram stain, KOH mount (fungi), Giemsa, culture on blood agar, Sabouraud's (fungi), chocolate agar
- Confocal microscopy (Acanthamoeba cysts)
- PCR for viral DNA (HSV)
Management:
Bacterial: Intensive topical fluoroquinolone (ciprofloxacin/moxifloxacin hourly); fortified antibiotics (tobramycin + cefazolin) for severe cases; cycloplegic (atropine) for pain
HSV: Topical aciclovir 3% ointment x5/day; oral acyclovir; avoid steroids alone
Fungal: Natamycin 5% drops (first-line for filamentous); voriconazole (Candida/severe); prolonged treatment 6-12 weeks
Acanthamoeba: PHMB (polyhexamethylene biguanide) + propamidine isethionate (Brolene) for months
General: No contact lens wear; cycloplegia for uveitis pain; analgesics; penetrating keratoplasty for perforations or refractory cases
9. Acute Iridocyclitis (Anterior Uveitis)
Definition: Acute inflammation of the iris (iritis) and ciliary body (cyclitis), collectively termed anterior uveitis or iridocyclitis. It is the most common form of uveitis.
Aetiology:
| Category | Examples |
|---|---|
| Idiopathic | Most common (50%) |
| HLA-B27 associated | Ankylosing spondylitis, Reiter's syndrome, psoriatic arthritis, IBD-associated arthritis |
| Infections | HSV, VZV, syphilis, tuberculosis, toxoplasmosis, CMV |
| Autoimmune | Sarcoidosis, Behcet's disease, juvenile idiopathic arthritis (JIA) |
| Trauma | Post-operative, penetrating injury |
Clinical Features:
Symptoms:
- Acute onset pain (aching, deep-seated)
- Photophobia
- Lacrimation (watering)
- Blurred vision
- Redness
Signs:
- Circumcorneal (ciliary) injection - injected vessels around limbus (deep flush)
- Keratic precipitates (KPs) - inflammatory cells deposited on corneal endothelium; fine = non-granulomatous; large "mutton-fat" KPs = granulomatous (sarcoidosis, TB)
- Flare and cells in anterior chamber (Tyndall effect) on slit lamp
- Small, irregular pupil (due to posterior synechiae - adhesions between iris and lens)
- Hypopyon - pus layer in lower anterior chamber (HLA-B27 type, Behcet's)
- Posterior synechiae - iris adheres to anterior lens capsule
- Iris nodules: Koeppe (at pupil margin), Busacca (on iris stroma) - granulomatous
- Reduced IOP (ciliary shutdown) or raised IOP (trabecular block)
Investigations:
- Slit-lamp examination (essential)
- Systemic workup: HLA-B27, ACE and CXR (sarcoidosis), FTA-ABS (syphilis), TB testing (Mantoux/IGRA)
Management:
Acute:
- Topical corticosteroids: Prednisolone acetate 1% (hourly initially, then taper) - mainstay
- Cycloplegic/mydriatic agents: Atropine 1% or cyclopentolate 1% - to prevent/break posterior synechiae, relieve ciliary spasm and pain
- NSAIDs: Topical ketorolac as adjunct
- Treat underlying cause if identified (e.g., anti-TB, antivirals for HSV)
Complications: Posterior synechiae, complicated cataract (PSC), secondary glaucoma, band keratopathy, cystoid macular oedema, optic disc oedema
(Kanski's Clinical Ophthalmology, p. 2471; Wills Eye Manual)
SECTION B (50 Marks)
Q1. PTERYGIUM (Long Answer - 10 Marks)
a) Define Pterygium (2 marks)
A pterygium (plural: pterygia; from Greek "pterygion" = wing) is a triangular fibrovascular sub-epithelial ingrowth of degenerative bulbar conjunctival tissue over the limbus onto the cornea. It is a progressive condition that grows from the interpalpebral zone (usually the nasal limbus) across the cornea towards the visual axis.
Histologically, it shows elastotic degenerative changes in vascularized subepithelial stromal collagen, and it invades the Bowman's layer of the cornea (unlike a pinguecula which does not cross the limbus).
(Kanski's Clinical Ophthalmology, p. 215)
b) Etiology and Types of Pterygium (3 marks)
Etiology
| Factor | Details |
|---|---|
| Ultraviolet (UV) radiation | Primary causative factor; UV-B causes oxidative damage and stimulates limbal stem cell dysfunction; explains tropical/equatorial distribution |
| Chronic dryness | Dry, dusty, windy environments |
| Genetic predisposition | Tends to run in families |
| Chronic conjunctival inflammation | May contribute to fibroblast activation |
| P53 mutations | Found in pterygium epithelium (UV-induced) |
Types / Classification of Pterygium
1. Based on morphology (Tan's classification):
- Type 1 (Atrophic): Thin; underlying episcleral vessels clearly visible; low risk of recurrence
- Type 2 (Intermediate): Partially obscures underlying vessels
- Type 3 (Fleshy/thick): Opaque; completely obscures vessels; high vascularity; high recurrence risk
2. True vs Pseudopterygium:
- True pterygium: Grows from limbus; firmly attached to underlying structures throughout its length; probe cannot be passed under its head
- Pseudopterygium: Band of conjunctiva adherent to cornea at its apex only (probe can be passed under its neck); caused by chemical burn, corneal ulcer, trauma, or cicatrizing conjunctivitis
3. Primary vs Recurrent pterygium
Parts of a pterygium (anatomy):
- Cap (head): Avascular, halo-like zone at advancing corneal edge
- Head: Firmly attached to cornea; Stocker line (iron deposition) just anterior to it
- Body: The fleshy triangular portion on the conjunctiva; contains blood vessels (Kanski's Clinical Ophthalmology, p. 215-216)
c) Management of Pterygium (3 marks)
Conservative (Medical) Management:
- UV protection: Sunglasses (UV-blocking); wide-brimmed hats
- Lubricating eye drops for dryness/irritation
- Topical steroids/NSAIDs during acute inflammation episodes (pingueculitis-like flares)
- Indications for surgery: visual impairment, significant astigmatism, recurrent inflammation, cosmetic concern, contact lens intolerance
Surgical Management:
1. Simple excision ("bare sclera" technique):
- Pterygium excised from cornea and conjunctiva, leaving bare sclera
- Simple to perform but high recurrence rate (~80%) and often more aggressive recurrence
- Not recommended as sole technique
2. Conjunctival Autografting (Gold Standard):
- Pterygium excised; a patch of conjunctiva (with or without Tenon's) harvested from the superior or upper-temporal limbal region of the same eye
- Graft sutured (10-0 nylon) or secured with fibrin glue (TISSEEL) into the bare area
- Recurrence rate significantly reduced (~5-15%)
- Fibrin glue shortens operating time and reduces post-operative irritation
3. Amniotic membrane transplantation:
- Used when conjunctiva is inadequate (bilateral pterygia, large recurrences)
- Provides anti-inflammatory and anti-scarring effects
4. Adjuvant therapies to reduce recurrence:
- Mitomycin C (MMC): Antimetabolite (0.02-0.04%); applied intraoperatively or postoperatively; inhibits fibroblast proliferation; risk of scleral melt if used incorrectly
- Beta-irradiation (Strontium-90): Postoperative radiation; inhibits fibroblast growth
- 5-Fluorouracil (5-FU) injections: Subconjunctival
5. Peripheral lamellar keratoplasty: For deep lesions involving corneal stroma
(Kanski's Clinical Ophthalmology, p. 216)
d) Complications of Pterygium (2 marks)
Pre-operative / If Left Untreated:
- Visual impairment: Encroachment on visual axis causes reduced vision
- Corneal astigmatism: Traction on corneal surface (often against-the-rule); may cause amblyopia in children
- Dellen formation: Localized corneal drying at the elevated leading edge
- Restricted ocular motility: Large/recurrent pterygia with subconjunctival fibrosis extending to fornices may limit extraocular movement
- Corneal scarring
- Cosmetic disfigurement
- Malignant transformation: About 2-10% with pterygium have coexisting squamous carcinoma (often unsuspected clinically) (Goldman-Cecil Medicine, p. 4126)
Post-operative Complications:
- Recurrence - most common complication (especially after bare-sclera technique; 80%); recurrent pterygia are more aggressive
- Graft oedema/retraction/loss
- Diplopia (from damage to extraocular muscles - especially medial rectus)
- Scleral melt/necrotising scleritis - rare but serious; after excessive MMC use
- Pyogenic granuloma at excision site
- Dellen at graft edge
- Infection / endophthalmitis (rare)
Short Notes - Section B (8 × 5 = 40 Marks)
2. Tonometry
Definition: Tonometry is the clinical measurement of intraocular pressure (IOP). It is a fundamental investigation in ophthalmology, particularly for the detection and monitoring of glaucoma.
Normal IOP: 10-21 mmHg (mean ~15.5 mmHg); readings >21 mmHg are considered ocular hypertension.
Types of Tonometers:
| Method | Principle | Details |
|---|---|---|
| Goldmann Applanation Tonometry (GAT) | Applanation (flattening) | Gold standard; measures force needed to flatten 3.06 mm area of cornea; requires slit lamp; fluorescein dye + cobalt blue light used |
| Non-contact (Air-puff) Tonometry | Applanation by air jet | No anaesthetic needed; useful for screening; less accurate; affected by corneal properties |
| Perkins Tonometry | Applanation (handheld version of GAT) | Useful for children, bedridden patients; requires anaesthetic |
| Schiotz (Indentation) Tonometry | Indentation | Plunger indents cornea; reading converted to mmHg via table; portable; less accurate; largely superseded |
| Tonopen | Electronic applanation | Portable; useful in scarred or irregular corneas |
| Dynamic Contour Tonometry (DCT) | Contour matching | Less affected by corneal thickness; measures pulsatile IOP |
| iCare (Rebound) Tonometry | Rebound | No anaesthetic; probe bounces off cornea; used in children and home monitoring |
Clinical Significance:
- Elevated IOP is the main modifiable risk factor for glaucoma
- Corneal thickness (CCT) affects GAT readings: thin cornea gives falsely low IOP; thick cornea gives falsely high IOP
- Diurnal variation: IOP is highest in the morning and lowest in the evening (Kanski's Clinical Ophthalmology)
3. Slit-Lamp Examination (Biomicroscopy)
Definition: The slit-lamp (biomicroscope) is a binocular microscope with an adjustable, high-intensity slit beam of light used for detailed examination of the anterior and posterior segments of the eye.
Components:
- Binocular microscope (variable magnification: 6x to 40x)
- Slit-beam illumination system - adjustable width, height, angle, and colour
- Chin rest and headband for patient positioning
Illumination Techniques:
| Technique | Use |
|---|---|
| Diffuse illumination | General overview; foreign bodies, conjunctival injection |
| Direct focal illumination | Corneal opacities, infiltrates, anterior chamber cells/flare |
| Retroillumination | Lens opacities (PSC, cortical cataract appear clearly); corneal foreign body |
| Specular reflection | Corneal endothelium |
| Sclerotic scatter | Subtle corneal oedema |
| Indirect (proximal) illumination | Corneal vascularisation |
Structures examined:
- Lids and lashes: Entropion, trichiasis, blepharitis
- Conjunctiva: Injection, papillae/follicles, chemosis, foreign bodies, pinguecula, pterygium
- Cornea: Keratic precipitates (KPs), ulcers (+ fluorescein), band keratopathy, arcus, oedema
- Anterior chamber: Cells, flare (Tyndall effect), hypopyon, hyphema
- Iris: Synechiae, nodules, rubeosis
- Lens: Cataract type, IOL position, posterior capsule opacity
- Vitreous: With Volk lens (+90D or +78D) or Goldmann 3-mirror lens for posterior segment and gonioscopy
Goldmann 3-mirror contact lens at slit lamp:
- Central mirror: posterior pole
- 73° mirror: peripheral retina
- 67° mirror: equatorial retina
- 59° mirror: gonioscopy (angle structures)
4. Ophthalmoscopy
Definition: Ophthalmoscopy (fundoscopy) is the examination of the internal structures of the eye, particularly the optic disc, retina, retinal vessels, and macula.
Types:
1. Direct Ophthalmoscopy:
- Provides an upright, virtual, magnified image (x15)
- Monocular; small field of view (~2 disc diameters)
- Good for optic disc assessment (cup:disc ratio), fundus details
- Easy to perform; portable; no dilated pupil mandatory (though helps)
- Technique: Patient looks at a distant target; examiner approaches to within 1-2 cm; uses +/- dioptre wheel to focus
2. Indirect Ophthalmoscopy:
- Produces an inverted, real image (x2-5)
- Wide field of view (up to 8 disc diameters with 20D lens) - better for peripheral retina
- Requires dilated pupil and a condensing lens (+20D or +28D)
- Binocular - allows stereoscopic view
- Superior for retinal detachments, peripheral lesions, examination in children
3. Slit-lamp with +90D / +78D lens:
- Highest magnification and stereopsis
- Best for macular and disc evaluation
- Requires dilated pupil
Findings assessed:
- Optic disc: Size, colour, margin, cup:disc ratio (N < 0.5), pallor, swelling
- Retinal vessels: A:V ratio (N = 2:3), AV nipping, copper/silver wiring
- Macula: Foveal reflex, haemorrhages, exudates, pigmentary changes
- Peripheral retina: Tears, holes, detachments, degeneration
5. Snellen Visual Acuity Chart
Definition: The Snellen chart is the standard clinical tool for measuring distance visual acuity. It was designed by Hermann Snellen (Dutch ophthalmologist) in 1862.
Principle:
- Standard testing distance: 6 metres (20 feet) - approximates optical infinity (parallel rays)
- Letters are designed so that the whole letter subtends 5 minutes of arc and each limb/stroke subtends 1 minute of arc at the specified distance
- The Snellen fraction: VA = Test distance / Distance at which that letter subtends 5' of arc
- e.g., 6/60 = patient reads at 6m what a normal eye reads at 60m
Recording:
- 6/6 (20/20) = normal vision
- 6/60 = only top letter readable (Snellen "big E")
- Worse than 6/60: Count Fingers (CF), Hand Movements (HM), Perception of Light (PL), No Perception of Light (NPL)
Components of the Chart:
- Letters decrease in size from top (largest) to bottom (smallest)
- Lines labelled by the distance at which normal eye reads them (6, 9, 12, 18, 24, 36, 60 metres)
- Uses optotypes (capital letters: C, D, E, F, H, K, N, P, R, U, V, Z) chosen for equal legibility
Performing the test:
- Occlude one eye at a time
- Patient stands at 6 metres (or uses mirror system)
- If patient cannot see 6/60: move to 3 metres (recorded as 3/60)
- Pinhole test: If VA improves with pinhole -> refractive error; if no improvement -> likely pathology
Limitations:
- Tests only central (foveal) vision
- Affected by lighting conditions
- Not suitable for children <3-4 years (use Kay pictures, Cardiff cards, or preferential looking)
- Illiteracy - use Tumbling E or Landolt C charts
LogMAR chart (Bailey-Lovie): More scientific alternative; equal number of letters per line; equally spaced letter and line separations; used in research.
6. Painful Blind Eye
Definition: A painful blind eye is a clinical syndrome where an eye that has lost all useful vision (no perception of light or minimal light perception only) develops persistent, intractable pain requiring active management.
Causes (why a blind eye becomes painful):
| Cause | Mechanism |
|---|---|
| Absolute glaucoma | End-stage glaucoma with very high IOP causing severe pain |
| Rubeotic (neovascular) glaucoma | Neovascularisation of angle (from ischaemia in DM, CRVO, OAI); very high IOP + haemorrhage |
| Phthisis bulbi | Shrunken, disorganised globe; aching, chronic pain |
| Endophthalmitis | Intraocular infection; severe pain |
| Sympathetic ophthalmia | Post-penetrating trauma; painful inflammation |
| Intraocular tumours | Secondary angle-closure glaucoma |
| Corneal exposure/degeneration | Neurotrophic corneal changes |
Management Options:
Medical:
- Cycloplegics (atropine 1%) - reduce ciliary spasm
- Topical beta-blockers, carbonic anhydrase inhibitors - reduce IOP in absolute glaucoma
- Retrobulbar alcohol injection (90% ethanol) or chlorpromazine - chemical ablation of ciliary nerves for pain relief (when vision has no potential)
- Systemic analgesics
Surgical (when medical fails):
- Cycloablation (cyclodiode laser / cyclocryotherapy) - destruction of ciliary body to reduce aqueous production and IOP
- Intravitreal absolute alcohol or gentamicin injection (chemical cyclodestruction)
- Enucleation (removal of entire eyeball) - definitive treatment; indicated when all other measures fail, or if intraocular malignancy suspected
- Evisceration (removal of intraocular contents, leaving scleral shell) - technically simpler; good cosmetic result; NOT performed if tumour suspected (risk of spreading)
7. Corneal Transparency
Definition: The cornea is normally transparent (crystal clear), allowing unimpeded transmission of light to the retina. This transparency is a unique optical property that depends on precise structural and physiological mechanisms.
Factors maintaining corneal transparency:
1. Structural factors:
- Regular collagen fibril arrangement: Collagen fibrils (type I) in the stroma are uniform in diameter (~22-30 nm) and arranged in regular parallel lamellae with equal spacing between fibrils. This regularity causes destructive interference of scattered light (Maurice's lattice theory), allowing only forward transmission of light.
- Avascularity of the cornea - no blood vessels to scatter light (maintained by VEGF inhibition at the limbus - "angiogenic privilege")
- Relative dehydration of the stroma (deturgescence): The stroma has a natural tendency to imbibe water (hydrophilic proteoglycans). Transparency requires the stroma to be maintained at ~78% water (not fully hydrated). This is achieved by:
- Corneal epithelium: Tight junctions form a barrier to water entry from tear film
- Corneal endothelium: Active Na+/K+ ATPase pump continuously removes water from stroma into aqueous humour ("pump-leak mechanism") - the most critical factor
2. Absence of myelin: Corneal nerves are unmyelinated (myelination would scatter light).
3. Absence of blood and lymph vessels.
4. Regular epithelial surface + precorneal tear film - creates a smooth refracting interface.
Causes of loss of corneal transparency:
- Oedema (endothelial failure, bullous keratopathy, acute angle-closure glaucoma)
- Scar (leucoma, macula, nebula)
- Infiltrate/abscess (bacterial, fungal, viral keratitis)
- Vascularisation (trachoma, interstitial keratitis)
- Degeneration (band keratopathy - calcium in Bowman's layer; arcus senilis - lipid deposition)
- Dystrophies (Fuchs endothelial dystrophy, granular dystrophy, macular dystrophy)
- Oedema after any endothelial damage (surgery, trauma)
8. Retinoscopy
Definition: Retinoscopy (also called skiascopy or shadow test) is an objective method of determining the refractive error of the eye without requiring subjective responses from the patient. It uses a retinoscope (streak or spot) to observe the movement of the reflex from the fundus.
Principle:
- A light beam is projected into the patient's eye; the light reflects back from the fundus as a "reflex"
- The examiner observes the movement of this reflex relative to the movement of the retinoscope beam
- Working distance: Conventionally 67 cm (1 metre also used); the working distance lens (+1.5D or +1.0D) is subtracted from the final reading
Observation of Reflexes:
| Reflex Movement | Interpretation |
|---|---|
| With movement (reflex moves in same direction as light) | Hyperopia, low myopia (beyond far point) |
| Against movement (reflex moves in opposite direction) | Myopia (between far point and examiner) |
| No movement (neutralisation point) | Far point at working distance; add +1.5D or +1.0D correction for actual refraction |
Streak Retinoscopy (Copeland/Welch-Allyn): More commonly used; can identify axis of astigmatism by rotating the streak - look for:
- "With" motion on both meridians = compound hyperopic astigmatism
- "Against" motion on both meridians = compound myopic astigmatism
- Mixed motion = mixed astigmatism
Advantages:
- Objective - no patient cooperation needed
- Especially valuable in: infants, young children, mentally challenged, patients who cannot communicate
- Most accurate method before prescribing glasses for children
Procedure:
- Cycloplegia (cyclopentolate 1% or atropropine 1%) recommended in children to relax accommodation
- Dim room; patient fixates distant target
- Examiner moves retinoscope beam vertically and horizontally; adds lenses until neutralisation
- Subtract working distance lens to get actual refractive error
9. Sudden Loss of Vision
Definition: Sudden loss of vision refers to an abrupt decrease in visual acuity or visual field occurring over minutes to hours, as distinct from gradual loss. It is an ophthalmic emergency requiring urgent evaluation.
Classification by Characteristics:
A. Painful Sudden Loss of Vision:
- Acute angle-closure glaucoma - very high IOP, halos, nausea/vomiting, hazy cornea
- Acute uveitis/iridocyclitis (usually mild-moderate vision loss)
- Endophthalmitis - severe pain, hypopyon
- Optic neuritis - pain on eye movement; young women; MS association; relative afferent pupillary defect (RAPD)
B. Painless Sudden Loss of Vision:
| Condition | Key Features |
|---|---|
| Central Retinal Artery Occlusion (CRAO) | Sudden, profound, painless loss; cherry-red spot at fovea; pale, oedematous retina; embolus/thrombosis; emergency (< 90 min window for treatment) |
| Central Retinal Vein Occlusion (CRVO) | "Blood and thunder" fundus; flame haemorrhages all 4 quadrants; disc oedema; variable vision loss |
| Retinal Detachment | Preceded by floaters + flashes (photopsia); then curtain/shadow obscuring vision; painless; Rhegmatogenous most common |
| Vitreous Haemorrhage | Sudden painless "floaters," "red haze," or "black dots"; red reflex absent; no fundal view; causes: DM, BRVO, retinal tear |
| Anterior Ischaemic Optic Neuropathy (AION) | Sudden altitudinal visual field loss; pale swollen disc; giant cell arteritis (arteritic AION) = ophthalmological emergency |
| Macular haemorrhage (wet AMD) | Sudden central vision loss; distortion (metamorphopsia); subretinal/sub-RPE bleeding |
| Amaurosis fugax | Transient (seconds-minutes) painless monocular loss ("curtain across eye"); due to carotid emboli; TIA equivalent |
| Hysterical/functional visual loss | Normal examination; no RAPD; young patients |
Investigations:
- Visual acuity; visual fields (confrontation, Humphrey perimetry)
- Pupil examination - RAPD indicates optic nerve/extensive retinal disease
- IOP measurement
- Slit-lamp + dilated fundus examination
- OCT (macular assessment)
- Fluorescein angiography (vascular occlusions)
- ESR/CRP, platelets (GCA)
- Carotid Doppler, echocardiogram, cardiac monitoring (for embolic causes)
- Neuroimaging (MRI brain) if optic neuritis or cortical cause suspected
Emergency Management:
- CRAO (< 90 min): Ocular massage, anterior chamber paracentesis, IOP-lowering agents, inhale CO2 + O2 mixture; thrombolytics (select patients)
- GCA / Arteritic AION: IV methylprednisolone immediately; prevent fellow eye involvement
- Acute angle closure: IV acetazolamide, topical beta-blocker, pilocarpine; urgent laser peripheral iridotomy
- Retinal detachment: Urgent surgical repair (pneumatic retinopexy, scleral buckle, vitrectomy)
*Sources: Kanski's Clinical Ophthalmology: A Systematic Approach (10th ed.); Goldman-Cecil Medicine International Edition; Wills Eye Manual (Office and Emergency Room Diagnosis and Treatment of Eye Disease); Robbins & Kumar Basic Pathology.*All questions answered. Here is a quick summary of what was covered:
What Was Answered (Both Sections, All Questions)
Section A - 50 Marks
Q1. Cataract (Long Answer - 10 marks):
- a) Definition - opacification of the crystalline lens
- b) Etiology (age-related, traumatic, metabolic, drug-induced, congenital, radiation, secondary) + Classification (by morphology: nuclear, cortical, PSC; by maturity: immature, mature, hypermature, Morgagnian)
- c) Signs & symptoms of senile cataract (painless vision loss, glare, monocular diplopia, "second sight," reduced red reflex, slit-lamp findings)
- d) Investigations (biometry, visual acuity, slit-lamp, IOP, fundus, B-scan) + Management (phacoemulsification as gold standard, SICS, ECCE, IOL implantation, complications)
Short Notes (Q2-9): Night blindness, Red eye, Chalazion, Subconjunctival haemorrhage, Myopia, Acute conjunctivitis, Keratitis, Acute iridocyclitis
Section B - 50 Marks
Q1. Pterygium (Long Answer - 10 marks):
- a) Definition - triangular fibrovascular subepithelial conjunctival ingrowth onto cornea
- b) Etiology (UV radiation, dryness, genetics) + Types (atrophic/intermediate/fleshy; true vs pseudopterygium; Tan's classification)
- c) Management (UV protection, conjunctival autografting as gold standard, adjuvant MMC/beta-irradiation, bare-sclera avoided due to 80% recurrence)
- d) Complications (astigmatism, visual axis involvement, recurrence, scleral melt from MMC, diplopia, squamous cell carcinoma risk 2-10%)
Short Notes (Q2-9): Tonometry, Slit-lamp examination, Ophthalmoscopy, Snellen visual acuity chart, Painful blind eye, Corneal transparency, Retinoscopy, Sudden loss of vision
Create a comprehensive ophthalmology study guide PDF for exam prep
Reading File
Running Command
ls /home/daytona/workspace/ 2>/dev/null && mkdir -p /home/daytona/workspace/ophthalmology-study-guide
This is a shared conversation. Sign in to Orris to start your own chat.