SMT N H L MEDICAL COLLEGE - OPHTHALMOLOGY INTERNAL EXAM

Complete Answers (Weighted by Marks)

SECTION 1

Q.1 (Attempt any 1 of 2) - 10 Marks

Option 1: Tear Film Layers & Their Functions + Causes & Management of Dry Eyes (5+5)

Part A: Layers of Tear Film and Their Functions (5 marks)

• Secreted by Meibomian glands (tarsal glands) and glands of Zeis
• Functions:
  • Prevents evaporation of aqueous layer
  • Provides smooth optical surface
  • Prevents overflow of tears over the lid margin
  • Antibacterial effect

• Secreted by main lacrimal gland (reflex secretion) and accessory lacrimal glands - glands of Krause and Wolfring (basal secretion)
• Functions:
  • Provides oxygen and nutrients to avascular corneal epithelium
  • Washes away debris and foreign bodies
  • Contains antibacterial substances - lysozyme, lactoferrin, IgA, beta-lysin
  • Provides smooth refracting surface

• Secreted by goblet cells of conjunctiva (densest in inferior nasal quadrant), crypts of Lieberkuhn, and surface epithelial cells
• Functions:
  • Converts hydrophobic corneal epithelium to hydrophilic surface - allows aqueous to spread
  • Traps debris and organisms
  • Lubricates the lids

Part B: Causes and Management of Dry Eyes (5 marks)

• Sjogren's syndrome (primary - dry eyes + dry mouth; secondary - associated with RA, SLE)
• Age-related lacrimal gland atrophy
• Riley-Day syndrome (familial dysautonomia)
• Post-irradiation, sarcoidosis, lymphoma infiltration
• Stevens-Johnson syndrome (scarring of accessory glands)
• Drug-induced: antihistamines, beta-blockers, atropine

• Vitamin A deficiency (xerophthalmia)
• Chemical burns (goblet cell destruction)
• Trachoma, pemphigoid (cicatrizing conjunctivitis)

• Meibomian gland dysfunction (blepharitis, rosacea)

• Lagophthalmos (exposure keratopathy)
• Bell's palsy (incomplete blinking)
• Exophthalmos

• Hydroxymethylcellulose (HMC) drops 4-6x/day
• Carbomer (Viscotears) gel - for moderate-severe
• Hyaluronic acid drops
• Preservative-free drops if using >4x/day

• Punctal occlusion - temporary (collagen plugs) then permanent (cautery or surgery)
• Moisture chamber spectacles

• Lid hygiene for meibomian gland dysfunction
• Vitamin A supplementation if deficient
• Treat blepharitis

• Humidifiers, avoiding drafts, air conditioning

• Cyclosporine 0.05% (Restasis) eye drops
• Short-course topical steroids for severe inflammation

Option 2: Labelled Diagram of Angle of Anterior Chamber + Management of POAG (4+6)

Part A: Angle of Anterior Chamber - Diagram Description (4 marks)

                    CORNEA
                       |
        Schwalbe's Line (anterior border of trabecular meshwork)
                       |
        Trabecular Meshwork (corneoscleral & uveal portions)
                       |
        Schlemm's Canal (posterior to trabecular meshwork)
                       |
        Scleral Spur (dense white band, posterior to Schlemm's canal)
                       |
        Ciliary Body Band (grey-brown, most posterior structure)
                       |
                    IRIS

1. Schwalbe's Line - thickened edge of Descemet's membrane, most anterior angle structure
2. Trabecular Meshwork - sieve-like structure; main site of aqueous drainage (~90%); pigmented in glaucoma
3. Schlemm's Canal - circumferential channel collecting aqueous, drains into episcleral veins
4. Scleral Spur - attachment of longitudinal ciliary muscle; landmark between ciliary body and trabecular meshwork
5. Ciliary Body Band - grey-brown band, widened in myopia
6. Iris root - most posterior

• Grade 4 (35-45 degrees) = wide open
• Grade 0 = closed/occludable

Part B: Management of Primary Open Angle Glaucoma (6 marks)

• Latanoprost 0.005% / Bimatoprost 0.03% / Travoprost - once nightly
• Mechanism: Increase uveoscleral outflow
• SE: Iris/periocular pigmentation, eyelash growth, iritis

• Timolol 0.5% BD (or 0.25% in elderly/respiratory disease)
• Mechanism: Reduce aqueous production
• SE: Bradycardia, bronchospasm, depression - CONTRAINDICATED in asthma/COPD

• Topical: Dorzolamide (Trusopt) 2% TDS, Brinzolamide 1% BD
• Systemic: Acetazolamide 250mg QDS (short-term, SE: hypokalemia, renal stones)
• Mechanism: Reduce aqueous production

• Brimonidine 0.2% BD-TDS
• Mechanism: Reduce aqueous production + increase uveoscleral outflow

• Pilocarpine 2-4% QDS - increase trabecular outflow
• SE: Miosis, brow ache, myopia

• Selective Laser Trabeculoplasty (SLT) - selective Q-switched Nd:YAG laser to trabecular meshwork; increases outflow; can repeat; equal to medications in early POAG (LiGHT trial)
• Argon Laser Trabeculoplasty (ALT) - older technique

• Trabeculectomy (filtration surgery) - guarded fistula from anterior chamber to subconjunctival space; with antimetabolites (MMC or 5-FU) to prevent scarring
• Tube shunts (drainage implants) - Ahmed, Molteno, Baerveldt valves for failed trabeculectomy
• Minimally Invasive Glaucoma Surgery (MIGS) - iStent, Hydrus, GATT
• Cyclodiode laser - destroys ciliary body; for refractory/painful glaucoma

Q.2 (Attempt any 2 of 3) - 12 Marks

Case 1: 20-year-old female, painful swelling with redness, right upper lid, 3 days (2+2+2)

a) Probable Diagnosis (2 marks)

• Hordeolum internum (internal stye) - points inside, more diffuse
• Acute chalazion (less tender, deeper, more central)
• Preseptal cellulitis (diffuse lid swelling, pyrexia, more systemic)

b) Common Predisposing Factors to Rule Out (2 marks)

• Staphylococcus aureus infection (most common cause)
• Poor lid hygiene / blepharitis
• Seborrhoeic dermatitis / rosacea
• Diabetes mellitus (impaired immunity - rule out with blood sugar)
• Immunosuppression (HIV, prolonged steroid use)
• Previous history of stye / chalazion
• Refractive error (squinting - rubbing of eyes)
• Anemia / general debility
• Poor nutritional status

c) Treatment Plan (2 marks)

1. Hot compresses - 10-15 min, 3-4 times/day (promotes pointing and drainage)
2. Lid hygiene - clean lash margin with diluted baby shampoo
3. Topical antibiotics - Chloramphenicol 0.5% drops or Tobramycin ointment QDS
4. Epilation of the involved lash (if follicle infection) - allows pus drainage
5. Incision and drainage - if pointing as abscess (under LA, incise at point of maximum fluctuation, stab incision parallel to lid margin)
6. Systemic antibiotics - Flucloxacillin/Amoxicillin-clavulanate if preseptal cellulitis develops
7. Treat underlying blepharitis / rule out DM

Case 2: 45-year-old driver, glare during night driving + dimness of vision in sunlight, gradually increasing over 6 months (2+2+2)

a) Probable Diagnosis (2 marks)

• Glare at night (due to light scatter from posterior subcapsular cataract - PSC is classic for glare/haloes)
• Dimness of vision in bright light (due to myopic shift or nuclear sclerosis)
• Gradual progression over months
• Age 45 (early onset may suggest nuclear sclerosis)

b) Morphological Classification of Cataract (2 marks)

c) Treatment Advice (2 marks)

1. Conservative: Increase lighting; anti-glare/polarized lenses; updated spectacles for temporary improvement
2. Surgical: Recommended once vision affects daily activities (driving, reading)
   • Phacoemulsification (PHACO) - gold standard: ultrasound emulsification of nucleus, through 2.2-2.8mm incision, foldable IOL implanted in capsular bag; minimal astigmatism, early visual rehabilitation
   • SICS (Small Incision Cataract Surgery) - manual, no-stitch, 5-7mm; preferred in hard nuclei, developing world
   • ECCE - older, large incision; rarely used
3. Post-operative care: Topical steroid + antibiotic combination (Pred-Tobra) for 6 weeks; eye shield at night
4. Driving advice: Should not drive until vision improves post-operatively and meets legal standard (6/12 with best correction)

Case 3: 50-year-old farmer, redness and fleshy tissue gradually increasing near nasal limbal area (2+2+2)

a) Differential Diagnosis (2 marks)

1. Pterygium (most likely) - fibrovascular triangular growth from nasal (or temporal) conjunctiva encroaching onto cornea; UV exposure + outdoor occupation strongly supports
2. Pingueculum - yellowish conjunctival thickening, does NOT cross limbus onto cornea; degenerative, UV-related
3. Pseudopterygium - conjunctival fold adherent to cornea after chemical/thermal burn or ulcer; probe can pass underneath (unlike true pterygium where probe cannot pass at limbus)
4. Conjunctival squamous cell carcinoma (SCC) - fleshy gelatinous limbal lesion; feeder vessels; must exclude
5. Pannus (in trachoma) - superficial vascular invasion of cornea from limbus (superior > nasal)

b) Clinical Features of Pterygium (2 marks)

• Appearance: Triangular fibrovascular sub-epithelial growth of degenerative bulbar conjunctival tissue, usually from nasal limbus (occasionally temporal), with 3 parts:
  • Cap - avascular grey zone ahead of the advancing head
  • Head - dense vascular apex on cornea
  • Body - fleshy vascular conjunctival fold
• Stocker's line - iron deposition line at advancing edge of pterygium (seen on slit lamp)
• Symptoms: Usually asymptomatic when small; grittiness and irritation from dellen effect; blurring of vision if encroaches visual axis; astigmatism; restricted EOM if severe fibrosis
• Histology: Elastotic degeneration of subepithelial collagen (same as pingueculum); invades Bowman's layer

• Grade 1: Limbus to <2mm cornea
• Grade 2: 2-4mm onto cornea
• Grade 3: >4mm or reaching pupil margin
• Grade 4: Covering pupil

c) Treatment Plan (2 marks)

1. Conservative (small/asymptomatic):
   • Sunglasses + UV protection
   • Artificial tears for dryness/irritation
   • Short-course topical steroids for inflammation
2. Indications for surgery: Encroachment on visual axis, significant astigmatism, restricted EOM, cosmesis, suspicious appearance
3. Surgical options:
   • Bare sclera technique - simple excision (high recurrence 30-80%, NOT preferred)
   • Conjunctival autograft - nasal pterygium excised, bare sclera covered with autologous conjunctiva from superior bulbar area; best results, recurrence < 5%
   • Amniotic membrane graft - for large/recurrent pterygia where conjunctival tissue is insufficient
   • Limbal stem cell graft - for severe recurrent cases
4. Adjuvant therapy to prevent recurrence:
   • Mitomycin-C (MMC) 0.02% - applied intraoperatively or postoperatively; reduces fibroblast proliferation (risk of scleral necrosis if overused)
   • Beta-irradiation (strontium-90) - postoperative
   • 5-Fluorouracil (5-FU) subconjunctival injections

Q.3 (Attempt any 3 of 4) - 18 Marks (6 marks each)

1. Intraocular Lenses (IOL) (6 marks)

1. Anterior Chamber IOL (ACIOL):
   • Placed in anterior chamber (in front of iris)
   • Angle-supported or iris-fixated
   • Used when posterior capsule is ruptured / no capsular support
   • SE: Corneal endothelial damage, angle damage, glaucoma
2. Posterior Chamber IOL (PCIOL):
   • Most commonly used
   • Placed in capsular bag (in-the-bag) or ciliary sulcus
   • Types: In-the-bag (standard), Sulcus fixated, Scleral fixated (suture or glued - for absent capsular support)

• PMMA (polymethylmethacrylate) - rigid, older, requires large incision
• Acrylic (hydrophilic/hydrophobic) - foldable, most commonly used today
• Silicone - foldable, but oil adhesion is problem if vitrectomy needed
• Collamer (STAAR) - used in phakic IOLs

• Monofocal - single focal length (distance correction standard); patient still needs reading glasses
• Multifocal - diffractive or refractive; corrects near and distance; potential dysphotopsia
• Extended Depth of Focus (EDOF) - Symfony IOL; reduces dysphotopsia vs multifocal
• Toric - corrects pre-existing corneal astigmatism
• Accommodating - attempts to simulate accommodation (Crystalens)

• Posterior chamber phakic IOL (ICL - Implantable Collamer Lens) - between iris and natural lens
• Anterior chamber phakic IOL - angle-supported or iris-claw (Artisan)

• Using keratometry (K readings) + axial length (A-scan biometry)
• SRK-II formula - traditional; P = A - (0.9K) - (2.5L) where A = A-constant of IOL
• SRK/T, Holladay, Hoffer-Q - 3rd generation; better for extreme eyes
• Barrett Universal II - 4th generation; most accurate currently
• Optical biometry (IOLMaster, Lenstar) - preferred over contact biometry

• Posterior capsule opacification (PCO) - "after cataract"; treated by Nd:YAG laser posterior capsulotomy
• IOL decentration/subluxation
• Bullous keratopathy (from ACIOL or endothelial touch)
• Glaucoma (from retained OVD, pupil block)
• Uveitis-Glaucoma-Hyphema (UGH) syndrome (ACIOL)
• Dysphotopsia (multifocal IOL)

2. Anterior Uveitis - Clinical Features and Management (6 marks)

1. Pain - dull, aching, periorbital; worse on accommodation
2. Photophobia - due to ciliary spasm
3. Lacrimation - reflex
4. Blurring of vision (if severe flare/fibrin in AC)
5. Redness - circumcorneal (ciliary/perilimbal injection - violaceous)

• Ciliary injection (perilimbal flush) - violaceous ring around cornea
• Keratic Precipitates (KPs) - white cells + fibrin deposits on corneal endothelium
  • Fine/stellate KPs - non-granulomatous (HLA-B27 associated)
  • Large "Mutton-fat" KPs - granulomatous (sarcoidosis, TB, VKH, HSV, toxoplasma)
  • Arlt's triangle distribution - inferior cornea
• Aqueous flare - Tyndall effect (protein leakage); graded 0-4
• Aqueous cells - white cells in AC; graded 0-4 (standard - SUN classification)
• Hypopyon - layered white cells in inferior AC (HLA-B27, Behcet's, endophthalmitis)
• Iris changes:
  • Posterior synechiae - adhesions between iris and lens (from fibrin)
  • Festooned/irregular pupil
  • Rubeosis iridis (neovascularization - late)
  • Koeppe nodules (at pupil margin) and Busacca nodules (iris stroma) - granulomatous
  • Iris atrophy (HSV, VZV uveitis)
• Reduced IOP (ciliary body shutdown - hypotony) or elevated IOP (trabecular blockage)
• Pupil: Small, irregular (miosis from spasm); may be occluded/secluded in chronic cases

• HLA-B27 associated - Ankylosing spondylitis (most common), Reiter's syndrome, psoriatic arthropathy, IBD
• Herpetic (HSV, VZV) - unilateral, recurrent
• Juvenile idiopathic arthritis (JIA) - insidious, no pain, white eye, girls
• Sarcoidosis - granulomatous
• Behcet's syndrome - hypopyon uveitis, recurrent
• Idiopathic (largest group, ~50%)

1. Topical steroids - Prednisolone acetate 1% hourly initially, taper over 4-6 weeks; most important treatment
2. Cycloplegics/Mydriatics (ESSENTIAL):
   • Atropine 1% BD or Cyclopentolate 1% TDS
   • Purpose: Relieve ciliary spasm (pain relief), prevent/break posterior synechiae, stabilize blood-aqueous barrier
3. NSAIDs - topical Ketorolac; systemic if unresponsive
4. Periocular steroids - subconjunctival/sub-Tenon's triamcinolone for severe/non-responsive
5. Systemic steroids - Prednisolone 1mg/kg/day for severe bilateral or posterior involvement
6. Immunosuppressives - Methotrexate, Azathioprine, Mycophenolate - for chronic/steroid-dependent/side effects
7. Treat underlying cause - Anti-TB for TB uveitis; Acyclovir for herpetic; Biologics (Anti-TNF) for HLA-B27/IBD

3. Acute Attack of Angle Closure Glaucoma (ACG) - Management (6 marks)

• Sudden severe eye pain, headache, nausea/vomiting
• Halos around lights (corneal edema), blurring of vision
• Red eye (circumcorneal injection)
• Mid-dilated, fixed, oval pupil
• Hazy, steamy cornea (edema)
• Shallow anterior chamber
• High IOP (40-70 mmHg)

• Acetazolamide (Diamox) 500mg IV stat, then 250mg oral QDS - most rapid
• Timolol 0.5% topically BD (if no contraindication)
• Brimonidine 0.1% topically BD
• Dorzolamide topically TDS

• Glycerol 50% oral 1-1.5g/kg (if not diabetic - hyperglycemic risk)
• Mannitol 20% IV infusion 1-2g/kg over 30 min (most effective for acute attack) - osmotic agent

• Pilocarpine 2-4% every 15 min initially - BUT only once IOP falls below 50 mmHg (above 50, iris is ischaemic and unresponsive; pilocarpine causes congestion and worsens attack initially)

• Prednisolone 1% to reduce inflammation

• Laser Peripheral Iridotomy (LPI) - Nd:YAG laser; creates hole in peripheral iris (usually superior, 11 or 1 o'clock position covered by lid); equalizes pressure between posterior and anterior chambers; eliminates pupillary block; treatment of choice
• Surgical iridectomy - if cornea too hazy for laser; peripheral iridectomy

• Prophylactic LPI to fellow eye - as 50% risk of acute attack in 5 years

• Continue topical medications until IPI done
• Post-LPI: examine angle (may still need antiglaucoma drops if residual angle damage/trabecular damage - "burned out" trabecular meshwork)
• Phacoemulsification (lens extraction) - definitive management especially in angle-closure due to phacomorphic/lens-induced; widens angle

4. Myopia (6 marks)

• Low myopia: < -3.00 D
• Moderate myopia: -3.00 to -6.00 D
• High myopia: > -6.00 D (pathological/degenerative myopia > -6 D)

1. Axial myopia (most common) - increased axial length; 1mm = 3D of myopia
2. Curvatural myopia - excessive corneal or lens curvature (keratoconus, buphthalmos)
3. Index myopia - increased refractive index of lens (nuclear sclerosis - "second sight" of the elderly, DM)
4. Positional myopia - forward displacement of lens

• Distance vision blurred; near vision clear
• Squinting to improve depth of focus
• Large, prominent-looking eyes (if axial)
• Deep anterior chamber
• Large optic disc with temporal crescent (peripapillary atrophy)
• Vitreous degenerations (floaters - Weiss ring) - more in high myopia

• Posterior staphyloma (ectatic weakness of posterior pole sclera)
• Lacquer cracks (breaks in Bruch's membrane at posterior pole)
• Foster-Fuchs spot (disciform hemorrhage/scar at macula)
• Rhegmatogenous retinal detachment (peripheral retinal degeneration - lattice degeneration with breaks)
• Subretinal neovascular membrane (choroidal neovascularization)
• Glaucoma (3x higher risk)
• Vitreous detachment / floaters
• Complicated cataract (nuclear type)
• Amblyopia (if high unilateral myopia in childhood)

• Spectacles (concave lenses) - most common, safe
• Contact lenses (soft/RGP) - better optical quality; orthokeratology (overnight RGP to flatten cornea temporarily)

• LASIK (Laser-Assisted In-Situ Keratomileusis) - most popular; flap created with microkeratome/femtosecond laser, excimer laser reshapes stroma; corrects up to -12D; rapid recovery
• PRK/LASEK/SMILE (see Section 2 Q.7)
• Phakic IOL (ICL) - for high myopia (-6D to -20D) where corneal thickness insufficient for LASIK
• Refractive lens exchange (RLE) - ECCE/PHACO + IOL; for extreme myopia; lose accommodation

• Low-dose Atropine 0.01% eye drops nightly - slows axial elongation
• Orthokeratology
• Peripheral defocus contact lenses/spectacles
• Increased outdoor time (protective - sunlight/dopamine release)

Q.4 (Attempt any 5 of 6) - 10 Marks (2 marks each, 2-3 sentences)

1. Marcus Gunn Pupil (Relative Afferent Pupillary Defect - RAPD)

2. Two Causes of Tunnel Vision

3. Two Indications for Enucleation

4. Snellen Chart

5. Blepharitis

6. Perimetry

SECTION 2

Q.5 (Attempt any 1 of 2) - 10 Marks

Option 1: Anatomy of Cornea + Management of HSV Keratitis (5+5)

Part A: Anatomy of Cornea (5 marks)

• Horizontal diameter: 11-12 mm; Vertical: 10-11 mm (slightly smaller)
• Central thickness: 0.5 mm; Peripheral: 0.7 mm
• Radius of curvature (anterior): 7.8 mm; (posterior): 6.8 mm
• Refractive index: 1.376

• Non-keratinized stratified squamous epithelium
• Cells: superficial flat cells, wing cells, basal columnar cells (only dividing cells)
• Basal cells attached to basement membrane by hemidesmosomes
• Undergoes complete turnover every 7 days (from limbal stem cells)
• Main barrier to water entry and infection

• Acellular, condensed anterior portion of stroma
• Type I and V collagen fibrils (irregular arrangement)
• Does NOT regenerate if damaged (replaced by scar/pannus)
• Absent in some species (not present in rabbits)

• 200-250 lamellae of parallel collagen fibrils (Type I collagen)
• Regular spacing maintained by proteoglycans (keratan sulphate, chondroitin sulphate) - key to transparency
• Keratocytes (modified fibroblasts) between lamellae
• Contains sensory nerves (from nasociliary branch of CN V1 - most densely innervated tissue in body)
• Transparency depends on regular lamellar arrangement + relative dehydration maintained by endothelial pump

• Basement membrane of corneal endothelium
• Type IV and VIII collagen
• Highly resistant to proteolytic enzymes, ulcers, and trauma
• Remnants: Haab's striae (horizontal breaks in buphthalmos), Fleischer ring (iron, base of keratoconus cone), Kayser-Fleischer ring (copper, Wilson's disease peripherally)

• Simple squamous cells, hexagonal mosaic pattern
• ~2500-3000 cells/mm² at birth; declines to ~1500 at age 80
• Does NOT regenerate - neighboring cells spread to fill gap (no mitosis in adults)
• Contains Na-K ATPase pump (active transport of fluid from stroma into AC) - maintains corneal dehydration and transparency
• Critical cell count: <500 cells/mm² = corneal decompensation/bullous keratopathy

Part B: Management of HSV (Herpes Simplex Virus) Keratitis (5 marks)

• Active viral replication in epithelium
• Dendritic ulcer - linear branching with terminal bulbs (pathognomonic)
• Fluorescein stains center; Rose bengal stains edges (devitalized cells)
• Treatment:
  • Topical Acyclovir 3% ointment 5x/day for 14 days - first line
  • Topical Ganciclovir 0.15% gel 5x/day - alternative
  • Trifluorothymidine (TFT) 1% drops 9x/day (available in some countries)
  • Mechanical debridement of infected epithelium (cotton swab) - removes viral load; adjunct
  • Oral Acyclovir 400mg 5x/day - alternative to topical
  • AVOID topical steroids in epithelial stage - worsens viral replication

• Immune-mediated, not direct viral
• Disciform edema with Descemet's folds; Khodadoust line (rejection line)
• May have Wessely immune ring
• Treatment:
  • Topical steroids (Prednisolone 1%) - to suppress immune reaction
  • Cover with antiviral (Topical Acyclovir 3% 3x/day) whenever steroids used - prevents epithelial reactivation
  • Taper steroids slowly (months)

• Loss of corneal sensation - decreased blink; exposure + neurotrophic
• Non-healing epithelial defect with rolled edges
• Treatment: Preservative-free lubricants, BCL (bandage contact lens), tarsorrhaphy, Cenegermin (recombinant nerve growth factor) drops

• Oral Acyclovir 400mg BD (or Valacyclovir 500mg OD) prophylaxis for >1 year
• The HEDS trial showed prophylactic oral Acyclovir reduces stromal keratitis recurrence by 50%
• Avoid triggers: UV, stress, fever, immunosuppression

• Penetrating Keratoplasty (PKP) / DALK (Deep Anterior Lamellar Keratoplasty) - for severe stromal scarring; risk of recurrence in graft

Option 2: Lacrimal Drainage System + Acute Dacryocystitis (5+5)

Part A: Lacrimal Drainage System - Diagram Description (5 marks)

Upper & Lower puncta (0.3mm, on papilla lacrimalis, 6mm from medial canthus)
         |
Upper & Lower canaliculi (vertical part 2mm, horizontal part 8mm)
         |
Common canaliculus (joins 90% - Valve of Rosenmuller at entry to sac)
         |
Lacrimal Sac (12-15mm; lies in lacrimal fossa - bone: lacrimal bone + frontal process of maxilla)
         |
Nasolacrimal Duct (NLD) (12-18mm; runs in bony NLD canal, exits at inferior meatus of nose)
         |
Hasner's valve (Plica lacrimalis - mucosal fold at nasal opening; failure to open = congenital NLD obstruction - CNLDO)

• Rosenmuller's valve - at junction of common canaliculus and lacrimal sac; prevents reflux
• Hasner's valve - at nasal end of NLD; prevents nasal secretions refluxing

Part B: Acute Dacryocystitis - Treatment (5 marks)

1. Systemic antibiotics - Amoxicillin-clavulanate (Co-amoxiclav) 625mg TDS for 7-10 days (first line); Flucloxacillin if Staphylococcal; IV antibiotics (Cefuroxime/Piperacillin-tazobactam) if severe cellulitis or sepsis
2. Hot compresses - 3-4 times daily to reduce inflammation and promote drainage
3. Topical antibiotics - Chloramphenicol drops QDS (adjunct)
4. Analgesics/NSAIDs for pain
5. Incision and drainage (I&D) - if abscess has pointing (fluctuant); stab incision to drain pus; do NOT probe during acute phase (risk of spreading infection, fistula)
6. Never probe during acute stage

• External DCR - skin incision, most reliable (~95% success)
• Endoscopic (endonasal) DCR - no skin scar, direct visualization; increasing popularity
• Silicone stents placed during DCR to maintain patency

1. Probing and syringing - for children with CNLDO (congenital NLD obstruction) up to 12-18 months

Q.6 (Attempt any 2 of 3) - 12 Marks

Case 1: 7-year-old boy, recurrent bilateral redness and itching every early summer (2+2+2)

a) Differential Diagnosis (2 marks)

1. Vernal Keratoconjunctivitis (VKC) - most likely; recurrent bilateral allergic conjunctivitis in young atopic males; seasonal (spring/summer); geographic areas (hot, dry climates)
2. Allergic (Seasonal Atopic) Conjunctivitis - bilateral, itching, watery discharge; associated with hay fever; less severe than VKC
3. Atopic Keratoconjunctivitis (AKC) - older patients, more severe, perennial, associated with atopic dermatitis
4. Giant Papillary Conjunctivitis (GPC) - contact lens wearers, less likely in a 7-year-old

b) Clinical Features of VKC (2 marks)

• Palpebral form: Giant papillae (>1mm) on upper tarsal conjunctiva - "cobblestone appearance"; flat-topped, hard; Trantas' dots (eosinophil accumulations at limbus in palpebral form)
• Limbal form: Gelatinous limbal thickening; Trantas' dots (white chalky deposits at limbus) - pathognomonic; more common in African/Asian patients
• Mixed form: Both
• Corneal involvement (Vernal keratopathy):
  • Superficial punctate keratitis (SPK) - superior cornea
  • Shield ulcer (oval/shield-shaped epithelial defect, upper cornea) - from large papillae rubbing
  • Plaque formation (calcified mucus in ulcer bed)
  • Pseudogerontoxon (white arc opacity)
• Discharge: Thick, ropy/stringy (due to eosinophil products and mucus)
• Smear: Eosinophilia (>2 eosinophils/HPF is diagnostic)
• Demographics: Young males (2:1 M:F), atopic background (asthma, eczema, rhinitis), warm climate, age 5-25

c) Treatment Plan (2 marks)

1. Avoid triggers - sunglasses, cold compresses, avoid rubbing eyes; indoors during peak allergy season
2. Topical mast cell stabilizers - Sodium Cromoglicate 2% drops QDS (mainstay, safe for long-term use); Lodoxamide 0.1% (more potent); Nedocromil; start before season for prophylaxis
3. Topical antihistamines - Olopatadine 0.1% BD, Azelastine, Ketotifen (dual action: antihistamine + mast cell stabilizer) - for acute itching relief
4. Topical steroids - Prednisolone 1% for acute severe exacerbation (short course); FML (fluorometholone) or Loteprednol preferred (less IOP rise); AVOID prolonged use (risk: steroid glaucoma, cataract)
5. Topical cyclosporine 0.05-2% - for steroid-dependent/refractory cases; spares steroids
6. Cold artificial tears - symptomatic relief, dilutes allergen
7. Oral antihistamines - for systemic allergic component
8. Shield ulcer treatment: Superficial keratectomy + BCL + topical antibiotic + steroid; Tacrolimus 0.03% ointment
9. Supratarsal steroid injection (betamethasone/triamcinolone) - for giant papillae in resistant cases

Case 2: 14-year-old boy, blunt trauma to right eye with tennis ball (2+2+2)

a) Possible Ocular Findings (2 marks)

• Hyphema - blood in anterior chamber (most common finding after blunt trauma; graded I-IV by AC fill)
• Subconjunctival hemorrhage (chemosis, BSCE)
• Corneal abrasion or edema/rupture (commotio corneae)
• Traumatic mydriasis/iridoplegia - dilated fixed pupil (sphincter rupture)
• Iridodialysis - tear of iris from its root
• Lens dislocation (subluxation/luxation) - phacodonesis, iridodonesis; torn zonules
• Traumatic cataract - rosette-shaped (posterior subcapsular)
• Hypotony (ciliary body shutdown) or elevated IOP (hyphema blocking angle)
• Angle recession (gonioscopic finding - late glaucoma risk)

• Commotio retinae (Berlin's edema) - retinal whitening (opalescent) at macula/posterior pole; from contre-coup; temporary, usually resolves
• Vitreous hemorrhage - blood in vitreous cavity
• Retinal tears/detachment - horseshoe tears especially at equator (retinal dialysis - at ora serrata, more common with blunt trauma)
• Choroidal rupture - concentric curved white arc temporal to disc; sub-retinal hemorrhage
• Optic nerve avulsion (severe)
• Orbital fracture (blow-out fracture - floor/medial wall) with enophthalmos, diplopia, infraorbital nerve anesthesia

b) Required Investigations (2 marks)

1. Visual acuity - Snellen chart; pinhole
2. Slit lamp examination - AC cells/flare, corneal status, lens position, hyphema grading
3. IOP measurement (Goldmann tonometry or rebound tonometer if corneal edema)
4. Gonioscopy - when hyphema clears; to assess angle recession, extent of trauma
5. Dilated fundus examination - indirect ophthalmoscopy for posterior segment (commotio, VH, retinal tears/detachment, choroidal rupture)
6. Ultrasound B-scan - if media opacity (vitreous hemorrhage, hypema) prevents fundus view; to detect retinal detachment/choroidal hemorrhage
7. CT scan orbit - to rule out orbital fracture, intraocular/intraorbital foreign body, optic nerve injury
8. Plain X-ray orbit (Caldwell + lateral) - if CT unavailable; for metallic FB
9. Colour fundus photography + OCT - for commotio retinae, choroidal rupture documentation

c) Treatment Plan (2 marks)

1. Hyphema management: Bedrest, bilateral eye shield, head elevation 30-45 degrees; topical steroid (Prednisolone 1% QDS) + cycloplegic (Atropine 1% BD); avoid aspirin/NSAIDs; monitor IOP daily; surgical washout (AC paracentesis) if: total hyphema, IOP >35mmHg for 48 hrs, or sickle-cell disease
2. Retinal tears: Laser photocoagulation (barrier laser) around tears before detachment occurs
3. Retinal detachment: Scleral buckling or vitrectomy depending on type and extent
4. Lens dislocation: Monitor if minor; pars plana lensectomy + vitrectomy if into vitreous; phacoemulsification if in AC
5. Orbital fracture: Conservative if no diplopia/enophthalmos; surgical repair (titanium mesh) after 10-14 days if significant
6. Vitreous hemorrhage: Conservative (observation) for 3 months; vitrectomy if non-clearing
7. Follow-up: Long-term monitoring for secondary traumatic glaucoma (angle recession glaucoma can manifest years later)

Case 3: 3-year-old child with white reflex (leukocoria) in right eye (2+2+2)

a) Differential Diagnosis of Leukocoria (2 marks)

1. Retinoblastoma - most common intraocular malignancy of childhood; MOST IMPORTANT to exclude
2. Congenital cataract - opacity of lens causing white reflex
3. Persistent Hyperplastic Primary Vitreous (PHPV) - now called PFVS (Persistent Fetal Vasculature Syndrome); unilateral, microphthalmia
4. Coats' disease - exudative retinal detachment with massive lipid exudation; young males, unilateral
5. Toxocara canis (ocular toxocariasis) - granuloma; usually 5-15 years
6. Retinopathy of Prematurity (ROP) - Stage 4-5 retinal detachment; premature baby history
7. Norrie's disease (rare X-linked)
8. Retinal detachment (any cause)

b) Investigation Planning (2 marks)

1. Ultrasound B-scan - detect intraocular mass, calcification (hyperechoic with acoustic shadowing = retinoblastoma); vitreous opacities; detect subretinal fluid (Coats')
2. MRI orbit and brain (preferred over CT in children - no radiation) - extent of retinoblastoma, optic nerve involvement, trilateral retinoblastoma (pineal gland); also detects intracranial extension
3. CT scan orbit - calcification in retinoblastoma (present in 95% - pathognomonic); less preferred due to radiation risk in children
4. Examination Under Anesthesia (EUA) - complete fundus evaluation with indirect ophthalmoscopy + scleral indentation; staging of retinoblastoma (IIRC/ABC staging)
5. Fluorescein Angiography (under GA) - vascular patterns in Coats', RB
6. Serum LDH, aqueous LDH - elevated in retinoblastoma
7. TORCH serology, Toxocara titres - for infectious causes
8. Genetic testing (RB1 gene mutation) - bilateral/familial retinoblastoma; counselling
9. Bone marrow biopsy + CSF - if extraocular spread suspected (metastatic workup)
10. Never biopsy an intraocular mass suspicious for retinoblastoma - risk of seeding

c) Treatment for Amblyopia (2 marks)

1. Remove the cause of deprivation first:
   • Dense cataract: Early surgery (ideally by 6-8 weeks for unilateral; 8-10 weeks bilateral) + IOL or contact lens for optical correction
   • Ptosis: Surgical correction
   • Retinoblastoma: Treat tumor, preserve eye if possible
2. Optical rehabilitation - accurate spectacle/contact lens correction immediately after cause removed (crucial for form deprivation amblyopia)
3. Patching (occlusion therapy) - patch the better/fellow eye to force use of amblyopic eye
   • Full-time patching for severe amblyopia (under 5 years): 6 hours/day
   • Patching protocols: 2 hours/day for mild, 6 hours for moderate-severe; older children may need longer
   • Monitor for reverse amblyopia in patched eye
4. Atropine penalization - 1% Atropine in better eye (1 drop/day on weekdays) to blur it; compliance is better than patching; as effective for moderate amblyopia (ATS trial)
5. Dichoptic therapy / binocular treatment - newer approaches (video games, specialized screens)
6. Critical period: Best prognosis if treated before age 7 (critical period); outcome worsens with age

Q.7 (Attempt any 3 of 4) - 18 Marks (6 marks each)

1. Corneal Refractive Surgeries (6 marks)

• Refraction (spectacle + cycloplegic), corneal topography/tomography (Pentacam), corneal thickness (pachymetry), endothelial cell count, pupil size in dim light, ocular examination

• Epithelium removed mechanically/with alcohol
• Excimer laser ablates directly on Bowman's + anterior stroma
• No flap - suitable for thin corneas, contact sports
• Recovery: Slower (3-4 days pain, BCL); final vision at 3-6 months
• SE: Pain, subepithelial haze (stromal wound healing), regression

• Epithelial flap preserved with dilute alcohol (18%), reflected, laser on Bowman's, flap replaced
• Less haze than PRK; modified form of surface ablation

• Corneal flap created with microkeratome (mechanical) or femtosecond laser (iLASIK/bladeless) to depth of ~100-160 microns
• Flap lifted, excimer laser applied to stromal bed, flap repositioned (adheres by IOP)
• Corrects: Myopia up to -12D, hyperopia up to +4D, astigmatism
• Criteria: Corneal thickness >500 microns; residual stromal bed >250 microns
• Advantages: Rapid visual recovery (24-48 hrs), minimal pain, no haze
• Complications: Flap complications (incomplete, free, buttonhole), diffuse lamellar keratitis (DLK/"Sands of Sahara"), epithelial ingrowth, ectasia (if residual bed thin), induced dry eye (cut corneal nerves)

• Femtosecond laser creates an intrastromal lenticule (lens-shaped tissue) + small arcuate incision (~2mm) - NO flap
• Lenticule extracted manually through small incision
• Advantages over LASIK: No flap (no flap complications), more corneal nerves preserved (less dry eye), biomechanically stronger cornea
• Currently approved mainly for myopia and myopic astigmatism
• Corrects up to -10D myopia

• Intracorneal Ring Segments (ICRS/Intacs/Keraring) - insert ring segments to flatten central cornea in keratoconus; improve BCVA; allow contact lens fitting
• Kamra inlay - for presbyopia (small aperture)

• Topical steroids (4-6 weeks) + topical antibiotics (1 week)
• Avoid contact sports, swimming for 2-4 weeks
• Sunglasses (UV protection)

2. Ptosis (6 marks)

• Mild: MRD1 ≥ 2mm (lid drop <2mm)
• Moderate: MRD1 1-2mm (lid drop 2-3mm)
• Severe: MRD1 ≤ 0mm (lid drop >4mm); lid covering pupil = amblyogenic

• 3rd nerve (CN III) palsy - complete ptosis + dilated pupil + EOM palsies (down and out); medical (DM, hypertension - pupil sparing) vs surgical (aneurysm - pupil involved)
• Horner's syndrome - mild ptosis (2mm) + miosis + anhidrosis; lesion of sympathetic pathway (cervical sympathetic chain, Pancoast tumor, carotid dissection)
• Marcus Gunn jaw-winking - synkinesis: ptosis elevates on jaw movement (pterygoid muscle contraction) - trigemino-oculomotor synkinesis

• Dehiscence/disinsertion of levator aponeurosis from tarsal plate
• Good levator function (>10mm); high lid crease; thinning of lid
• Causes: Senile (most common adult ptosis), post-op (after cataract surgery), contact lens wearers, pregnancy

• Congenital ptosis (most common in children) - maldevelopment of levator muscle; poor levator function; lid lag in down gaze; absent lid crease
• Myasthenia Gravis - fatigable ptosis; Tensilon test positive; bilateral, variable; ice test positive
• Myotonic dystrophy, CPEO (chronic progressive external ophthalmoplegia) - bilateral ptosis + EOM palsy; Kearns-Sayre syndrome (with pigmentary retinopathy)

• Weight of lid from tumor, dermatochalasis, hemangioma, lymphoma, edema

• Laceration of levator, post-surgical, haematoma

• MRD1, MRD2
• Levator function (LF) - most important: >10mm excellent, 5-10mm moderate, <4mm poor
• Upper lid crease height
• Bell's phenomenon (upward rotation of eye on lid closure - protective for surgical planning)
• Corneal sensation
• Hering's law (bilateral testing - upper lid elevator muscle symmetry)
• Jaw-winking test (Marcus Gunn)
• Tension test / ice test (Myasthenia)

• Mild ptosis + good LF: Fasanella-Servat (resection of tarsus + Muller's muscle) - especially Horner's
• Moderate-severe + good LF: External levator resection via skin crease approach

3. Colour Vision (6 marks)

• S-cones (Short, ~420nm) - blue/violet
• M-cones (Medium, ~530nm) - green
• L-cones (Long, ~560nm) - red

• Anomalous trichromats - need abnormal ratios to match colours
  • Protanomaly - red weakness (L-cone abnormal)
  • Deuteranomaly - green weakness (M-cone abnormal) - most common colour defect
  • Tritanomaly - blue weakness (S-cone abnormal) - rare, acquired

• Protanopia - absent L-cones; confuse red-green; red appears dark (luminosity loss)
• Deuteranopia - absent M-cones; confuse red-green; red not dark
• Tritanopia - absent S-cones; confuse blue-yellow; very rare; often acquired

• Rod monochromacy - only rods; complete colour blindness; photophobia, nystagmus, low VA
• Cone monochromacy - one cone type only

• Red-green CVD: X-linked recessive; males 8% (Caucasian), females 0.5%
• Blue-yellow (Tritan): Autosomal dominant; rare
• Congenital vs Acquired: Congenital = usually red-green; Acquired = usually blue-yellow (glaucoma, diabetic maculopathy, optic nerve disease)

• Occupational screening: Pilots, drivers, electricians, military - must have normal colour vision
• Inherited CVD: No treatment; counselling; accommodations
• Acquired CVD: Treat underlying cause; monitor disease progression

4. Keratoconus (6 marks)

• Eye rubbing (strong association) - chronic rubbing destroys keratocytes
• Atopy (eczema, vernal KC, allergic disease) - >50%
• Down syndrome (trisomy 21)
• Connective tissue disorders - Marfan's, EDS
• Leber's congenital amaurosis
• Mitral valve prolapse
• Genetics: AD with variable penetrance; several loci identified

• Thinning of corneal stroma (keratocyte loss + reduced collagen fibrils)
• Breaks in Bowman's layer
• Epithelial iron ring (Fleischer ring) at base of cone
• Horizontal stress lines in stroma (Vogt's striae) - tension in stretched stroma
• Descemet's membrane can rupture - acute hydrops

• Progressive myopia (axial type - but irregular)
• Irregular astigmatism (often against-the-rule, difficult to correct with spectacles)
• Monocular diplopia/polyopia
• Glare and halos
• Recurrent changes in spectacle prescription

• Fleischer ring - iron deposition (haemosiderin) in epithelium at base of cone - seen with cobalt blue filter
• Vogt's striae - fine vertical stress lines in deep stroma; disappear on pressure (Munson's sign)
• Apical scarring - subepithelial, at apex of cone (white/grey opacity)
• Munson's sign - V-shaped deformity of lower lid on down-gaze (apical protrusion pushing lid)
• Rizutti's sign - conical reflection on nasal cornea when light shone from temporal side (pear-shaped reflection)
• Apical thinning - best seen on slit lamp or pachymetry
• Acute hydrops - sudden break in Descemet's, aqueous floods stroma; acute pain, photophobia, severe blurring, corneal edema; resolves with scarring over weeks

• Inferior steepening, increased K readings (>47D)
• Skewed bow-tie pattern, inferior-superior asymmetry (I-S value >1.4D)
• Posterior corneal elevation (more sensitive on Scheimpflug imaging)
• Thinnest point below normal

• Regular spectacles for early stages

• Rigid Gas-Permeable (RGP) contact lenses - most important; vault over cone, create smooth refracting surface
• Hybrid lenses (RGP centre + soft skirt)
• Scleral lenses - vault entire cornea; best for advanced/irregular/intolerant of RGP; most comfortable

• Riboflavin 0.1% + UVA irradiation (365nm, 3mW/cm² for 30 min) - standard Dresden protocol
• Creates new covalent bonds between collagen fibrils (strengthens/stiffens cornea)
• Only treatment that halts progression - does not improve vision significantly but prevents worsening
• Indications: Progressive keratoconus (>0.5D K change/year OR >0.5D thinning)
• Minimum corneal thickness: 400 microns (to protect endothelium)
• Epithelium-off (standard) vs epithelium-on (transepithelial; less effective)
• Accelerated CXL - higher irradiance, shorter time (equivalent total energy)

• Semicircular PMMA ring segments implanted in mid-peripheral stroma
• Flatten central cone, reduce myopia/astigmatism
• Allow better contact lens fit
• Combined with CXL (CXL+INTACS)

• Deep Anterior Lamellar Keratoplasty (DALK) - replace diseased stroma, preserve healthy endothelium; preferred as avoids endothelial rejection; Big bubble technique (Anwar)
• Penetrating Keratoplasty (PKP) - full thickness corneal transplant; for extensive disease with endothelial involvement or failed DALK; graft survival ~90% at 10 years; risk of rejection
• Topography-guided ablation (TOPOGUIDED PRK) + CXL - for mild-moderate with good thickness

Q.8 (Attempt any 5 of 6) - 10 Marks (2 marks each, 2-3 sentences)

1. Gonioscopy

2. Allergic Conjunctivitis

3. Leukocoria

4. Two Causes of Decreased Corneal Sensation

5. After Cataract (Posterior Capsule Opacification - PCO)

6. Two Causes of Painful Red Eye

Marks Summary & Strategy Guide