## Cortical vs. Nuclear Sclerotic Cataract: Key Discriminators **Key Point:** The location of onset and direction of progression are the PRIMARY distinguishing features between cortical and nuclear cataracts. ### Cortical Cataract 1. **Onset:** Periphery of the cortex (equatorial region) 2. **Progression:** Centripetal (toward the nucleus) 3. **Appearance:** White or grayish opacities; may show radial spokes or riders 4. **Color:** Initially white, later may show brown tinge 5. **Nuclear involvement:** Late (nucleus remains clear initially) ### Nuclear Sclerotic Cataract 1. **Onset:** Central nucleus 2. **Progression:** Centrifugal (outward, but nucleus hardens) 3. **Appearance:** Hard, dense nucleus 4. **Color:** Amber-brown or dark brown (brunescent) 5. **Cortex:** Often remains relatively clear initially ### Comparative Table | Feature | Cortical | Nuclear Sclerotic | |---------|----------|-------------------| | **Site of onset** | Periphery (equator) | Central nucleus | | **Direction** | Centripetal | Centrifugal (hardening) | | **Color** | White → gray → brown | Amber → brown → dark brown | | **Nucleus hardness** | Normal initially | Hard, dense | | **Myopic shift** | Minimal | Marked ("second sight") | | **Glare symptoms** | Prominent | Less prominent | | **Speed of progression** | Variable | Slow | **High-Yield:** Cortical cataracts present with **peripheral onset and centripetal spread**; nuclear cataracts present with **central hardening and browning**. This is the gold-standard discriminator. **Clinical Pearl:** Cortical cataracts often cause more glare and difficulty with bright light (due to peripheral opacities scattering light), whereas nuclear cataracts cause more difficulty with dim light and near vision due to hardening of the lens nucleus. **Mnemonic:** **CORN** = **C**ortical **O**nset at peRiphery, **N**uclear at ceNter. 
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