Lens and Cataract
Core concepts
Know lens anatomy (capsule, cortex, nucleus) and the types of cataract: nuclear sclerotic, cortical, posterior subcapsular, and traumatic. Understand risk factors: age, diabetes, steroids, UV, trauma, smoking. Know that posterior subcapsular cataract causes early glare and is common with steroids.
Understand indications for cataract surgery (visual function, not just acuity), biometry for intraocular lens power, and complications: endophthalmitis, posterior capsule rupture, retinal detachment, and refractive surprise. Know that pseudophakic bullous keratopathy follows endothelial damage.
Traps
- Assuming cataract surgery is always indicated by acuity alone.
- Forgetting that posterior subcapsular cataract causes disproportionate glare.
- Mixing up endophthalmitis (early, severe) with sterile inflammation.
- Ignoring biometry errors as a cause of refractive surprise.
Rule of thumb
If a patient has glare and difficulty with night driving but good Snellen acuity, suspect posterior subcapsular cataract.
Worked example
A patient on long-term steroids develops glare and reduced contrast sensitivity. Slit lamp shows posterior subcapsular opacity. Plan cataract surgery after biometry and discuss IOL options.