🔬 Lens — Anatomy & Basic Science

1. Anatomy of lens + mechanism of accommodation — Biconvex avascular structure; accommodation via ciliary muscle contraction → zonule relaxation → lens becomes more convex (near focus)
2. Embryology of lens — Develops from surface ectoderm; lens placode → lens vesicle → lens
3. Transparency of lens — Maintained by: avascular structure, crystallin proteins, pump-leak mechanism (Na⁺/K⁺ ATPase), UV absorption by crystallins
4. Constituents of lens — Capsule (thickest basement membrane in body), epithelium (single layer, equatorial mitosis), lens fibers (crystallins, no nucleus)

🔵 Cataract — General

1. Define & classify cataract — Opacity of lens/capsule. Types: congenital, developmental, senile, traumatic, complicated, toxic, secondary
2. Causes of gradual, painless, progressive diminution of vision (DOV) — Senile cataract, POAG, diabetic retinopathy, ARMD, optic atrophy
3. Congenital cataract: types, clinical features, causes in 2-year-old — Types: lamellar (most common), polar, nuclear, sutural. Cause in 2yr: TORCH infections, galactosemia, Down syndrome. Feature: leukocoria
4. Senile cataract: clinical stages + symptoms — Immature (cortical/nuclear) → Mature (white, uniform opacity) → Hypermature (Morgagnian/shrunken). Stages: Immature, Mature, Hypermature (Morgagnian). Symptoms: blurred vision, glare, myopic shift
5. Second sight phenomenon — Nuclear sclerosis increases refractive index → acquired myopia → presbyopic patient can read without glasses temporarily

🔧 Cataract Surgery

1. Phacoemulsification — Ultrasonic fragmentation of nucleus through small incision (~2.8mm). Merits: fast recovery, sutureless, less astigmatism. Demerits: steep learning curve, costly, risk of posterior capsule rupture. Main steps: capsulorhexis → hydrodissection → nucleus emulsification → cortex aspiration → IOL implantation
2. Late post-op complications of ECCE — PCO (after-cataract), astigmatism, IOL decentration, cystoid macular edema (CME), late endophthalmitis
3. Pre-op preparation & evaluation for cataract surgery — Visual acuity, slit-lamp, keratometry, biometry (IOL power by SRK formula), blood sugar, BP, consent, topical antibiotics

🔴 Post-Surgery Complications & Special Topics

1. After-cataract (PCO): definition & treatment — Posterior capsule opacification due to residual LECs proliferating. Tx: Nd:YAG laser capsulotomy
2. Complications: shallow AC after cataract surgery + lens position anomalies — Shallow AC causes: wound leak, choroidal detachment, pupillary block. Lens anomalies: subluxation, dislocation (in-the-bag vs out-of-bag)
3. Aphakia: definition, causes, optical correction — Absence of lens. Causes: surgical, traumatic, congenital. Correction: +10D spectacles, contact lens, IOL, epikeratophakia
4. Problems with aphakic spectacle correction — +8–10D lens: 25–30% magnification, ring scotoma, roving ring, pincushion distortion, poor cosmesis; monocular aphakia not correctable with glasses

📍 Lens Position Anomalies

1. Subluxation/dislocation: causes, c/f, management — Causes: Marfan's, homocystinuria, trauma, Weill-Marchesani. C/F: iridodonesis, phacodonesis, monocular diplopia, glaucoma. Mx: spectacle correction or surgical removal
2. Syndromes: ophthalmic findings in homocystinuria & Weill-Marchesani — Homocystinuria: lens dislocates down & in, glaucoma, retinal detachment. Weill-Marchesani: lens dislocates down, microspherophakia, pupillary block glaucoma
3. Sunset syndrome — IOL sinks inferiorly due to capsular bag contraction/zonular dialysis; sunset = inferior displacement; sunrise = superior
4. Microspherophakia — Small spherical lens; increased refractive power, high myopia, pupillary block glaucoma; seen in Weill-Marchesani, Marfan's
5. Ectopia lentis: causes & management — Causes: Marfan's (up & out), homocystinuria (down & in), trauma. Mx: refraction, surgical if vision impaired
6. Difference between aphakia & pseudophakia — Aphakia: no lens (+10D correction, high magnification). Pseudophakia: artificial IOL in place (near-normal vision, minimal distortion)
7. Methods to correct aphakia post cataract surgery — Spectacles, contact lens, IOL (PCIOL, ACIOL, iris-clip), epikeratophakia
8. Late post-op complications of cataract surgery — PCO, CME, retinal detachment, IOL decentration, endophthalmitis (late/chronic), bullous keratopathy

🧩 Special Types

1. Complicated cataract: causes & c/f — Due to intraocular disease (uveitis, POAG, CRVO, retinitis pigmentosa, etc.). Starts as posterior subcapsular opacity → progresses anteriorly
2. Difference between mature & hypermature cataract — Mature: uniform white opacity, no fundal glow. Hypermature: cortex liquefied, nucleus settles (Morgagnian) or shrunken (Wrinkled capsule)
3. Treatment of post-op endophthalmitis — Intravitreal vancomycin + ceftazidime/amikacin ± dexamethasone. Pars plana vitrectomy (PPV) if VA = light perception only (EVS trial)

📋 Clinical Scenarios

1. 54M, sudden painful loss of vision RE, hypopyon, h/o phaco + IOL few days back → Diagnosis & Mx — Acute post-op endophthalmitis. Mx: urgent intravitreal antibiotics ± PPV per EVS guidelines
2. 60M, cataract surgery 2 days ago, visual reduction + severe pain → Most likely diagnosis — Acute post-op endophthalmitis (most common organism: S. epidermidis)
3. Dilating drops used in ophthalmology — Tropicamide 1% (short-acting mydriatic), cyclopentolate 1% (cycloplegic), atropine 1% (longest cycloplegic), phenylephrine 5%/10% (mydriatic only)
4. 70M, gradual painless DOV RE+LE ×2yrs, VA RE=6/60, LE=6/24, near vision improved, used to need +2.5D now reads without glasses → Diagnosis, examination steps, surgical procedure, early post-op complications — Nuclear sclerosis cataract (second sight). Exam: slit lamp, keratometry, biometry. Surgery: phacoemulsification + PCIOL. Early complications: wound leak, hyphema, corneal edema, IOP spike, PCR
5. 50M, poorly controlled diabetic, sudden pain + redness + marked ↓ vision LE, operated at eye camp 3 days ago for cataract → D/D, 3 preventive measures — Post-op endophthalmitis vs. acute angle closure. Prevention: strict asepsis, pre-op povidone-iodine, post-op antibiotics, proper patient selection, glucose control pre-op

Lens — Basic Science

• Capsule: Thickest basement membrane in body
• Epithelium: Single layer, mitosis at equator
• Fibers: Filled with crystallins, lose nucleus on maturation

Cataract — General

• Immature: Partial opacity, some red reflex
• Mature: Complete white opacity, no red reflex
• Hypermature: Cortex liquefied; Morgagnian (nucleus sinks) or shrunken capsule Symptoms: Blurred vision, glare, monocular diplopia, myopic shift.

Cataract Surgery

Post-Surgery Complications

Aphakia

Lens Position Anomalies

• Homocystinuria: Lens dislocates down & in, glaucoma, retinal detachment, thromboembolism
• Weill-Marchesani: Lens dislocates down, microspherophakia, pupillary block glaucoma, brachydactyly

1. Aphakic spectacles (+10D)
2. Contact lens
3. IOL (PCIOL — preferred, ACIOL, iris-clip)
4. Epikeratophakia (keratorefractive)

Special Types of Cataract

Clinical Case Scenarios

• Tropicamide 1%: Short-acting mydriatic + weak cycloplegic
• Cyclopentolate 1%: Cycloplegic (children's refraction)
• Atropine 1%: Longest cycloplegic (uveitis, amblyopia)
• Phenylephrine 5%/10%: Mydriatic only (no cycloplegia)

1. Pre-op povidone-iodine 5% conjunctival wash
2. Strict surgical asepsis + proper instrument sterilization
3. Pre-op blood sugar control; post-op topical/systemic antibiotics