Cataract and Refractive Surgery
This domain tests cataract types, phacoemulsification, biometry, postoperative complications, and refractive surgery selection. Safety and contraindications are heavily tested.
Core cataract surgery
- Cataract types: nuclear sclerotic (yellow-brown), cortical (spokes), posterior subcapsular (diabetes, steroids). Surgery is phacoemulsification with capsulorrhexis and in-the-bag IOL placement.
- Biometry uses axial length, keratometry, and a formula such as Barrett or SRK/T for normal eyes.
- Complications include posterior capsule rupture, vitreous loss, retained cortex, and endophthalmitis (0.03–0.1%; coagulase-negative Staphylococcus). Endophthalmitis presents day 2–7 with pain and hypopyon; treat with vitreous tap and intravitreal vancomycin plus ceftazidime.
- TASS is sterile, appears day 1, and responds to steroids.
- Posterior capsular opacification is treated with YAG capsulotomy; risks include retinal detachment and IOL pitting.
Refractive surgery
- LASIK uses a flap and gives faster recovery; PRK is surface ablation; SMILE uses a small incision.
- Contraindications: unstable refraction, severe dry eye, keratoconus or ectasia, autoimmune disease, pregnancy.
- ICL is an option for high myopia or thin corneas.
Worked example
A 60-year-old has pain and vision loss 3 days after uneventful phaco with a hypopyon. Reasoning: timing and hypopyon favor endophthalmitis over TASS, which is typically day 1 and often painless. Obtain a vitreous sample, inject intravitreal antibiotics, and consider vitrectomy if vision is light perception only.
Traps
Not every postoperative inflammation is infection. YAG treats PCO, not corneal edema. Do not perform refractive surgery on a keratoconic topography.