Classification of Cataracts
Ophthalmology High-Yield Essentials
1. Anatomical Classification
| Type | Clinical Characteristic |
|---|---|
| Nuclear | Central opacity causes myopic shift (“second sight”). |
| Cortical | Peripheral “wedge” or “spoke-like” opacities. |
| Posterior Subcapsular | Located just under the posterior capsule; causes significant glare. |
2. Etiological Classification
- Senile (Age-related): Most common; progressive hardening of the lens.
- Metabolic: Diabetes (osmotic hydration), Hypocalcemia (tetany/cataracts), Galactosemia.
- Traumatic: “Rosette-shaped” cataract following blunt ocular trauma.
- Toxic: Steroid-induced (specifically posterior subcapsular), Amiodarone, Chlorpromazine.
- Congenital: Often associated with maternal infections (Rubella – “pearl-like” opacities).
3. NEET PG High-Yield Pearls
- Myopic Shift: Nuclear sclerosis increases the refractive index of the lens, making the patient temporarily need weaker reading glasses or better near vision.
- Posterior Subcapsular Cataract: Highly associated with systemic corticosteroid use and ionizing radiation.
- Diabetes: Two types: True diabetic cataract (snowflake/osmotic, rapid) and Age-related cataract (occurs earlier in diabetics).
- Resource: For more detailed clinical images and question banks on these types, visit mymedschool.org.