Vitamin A Deficiency (Xerophthalmia)
Ophthalmology & Public Health High-Yield Essentials
1. WHO Classification (X-Stages)
| Stage | Clinical Finding |
|---|---|
| XN | Night blindness (Nyctalopia) – Earliest symptom. |
| XA | Conjunctival xerosis (dry, dull appearance). |
| XB | Bitot’s spots (foamy, triangular, keratinized deposits). |
| XD | Corneal xerosis. |
| XE | Corneal ulceration / Keratomalacia (Liquefaction necrosis). |
2. High-Yield Pearls
- Pathophysiology: Vitamin A is essential for the production of rhodopsin (in rods) and maintaining the integrity of mucus-secreting epithelium.
- Keratomalacia: The most severe stage of xerophthalmia, representing a true ophthalmic emergency. Leads to rapid perforation and blindness.
- Public Health: Vitamin A supplementation is a cornerstone of child survival strategies in endemic regions.
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