A 68-year-old man from Delhi presents with progressive blurring of vision over 3 years. He reports difficulty with night driving and glare from headlights. On examination, visual acuity is 6/18 in both eyes. Slit-lamp examination reveals a brown discoloration of the lens nucleus with preserved clarity of the cortex. The patient denies any history of trauma, uveitis, or systemic disease. What is the most likely type of cataract?

Explanation

## Clinical Presentation Analysis **Key Point:** The combination of brown discoloration of the nucleus, progressive vision loss over years, and difficulty with glare in an elderly patient is pathognomonic for nuclear sclerotic cataract. ### Distinguishing Features of Nuclear Sclerotic Cataract | Feature | Nuclear Sclerotic | Cortical | Posterior Subcapsular | |---------|-------------------|----------|----------------------| | **Colour** | Brown/amber nucleus | White opacities | Granular/vacuoles | | **Location** | Central nucleus | Peripheral cortex | Posterior subcapsular | | **Symptom onset** | Gradual, years | Variable | Rapid, months | | **Glare** | Marked (myopic shift) | Minimal initially | Severe | | **Night vision** | Severely affected | Relatively preserved | Severely affected | | **Refractive change** | Myopic shift | Hyperopic shift | Minimal | **Clinical Pearl:** The brown/amber appearance of the nucleus is due to cross-linking of lens proteins and accumulation of chromophores over decades. This is the most common age-related cataract type. **High-Yield:** Nuclear sclerotic cataracts cause a **myopic shift** in refraction — patients may report temporary improvement in near vision ("second sight of the aged") before vision deteriorates. This distinguishes it from cortical cataracts, which cause hyperopic shift. ### Why This Patient Has Nuclear Sclerotic Cataract 1. **Age and duration:** 68 years old with 3-year progressive course — typical for age-related nuclear sclerosis 2. **Brown nucleus on slit-lamp:** Pathognomonic finding 3. **Preserved cortical clarity:** Rules out cortical cataract 4. **Glare and night driving difficulty:** Characteristic of nuclear opacity blocking light transmission 5. **No trauma/uveitis history:** Rules out secondary causes [cite:Khurana Textbook of Ophthalmology Ch 8]