Vitamin A deficiency is the leading cause of preventable childhood blindness worldwide. Its clinical features include:

• Night blindness (nyctalopia) — earliest sign
• Bitot's spots — foamy white deposits on conjunctiva
• Xerophthalmia — dry eyes due to reduced tear production
• Keratomalacia — corneal ulceration leading to blindness (severe)
• Increased susceptibility to infections

Other deficiency diseases: Rickets = Vitamin D; Scurvy = Vitamin C; Pellagra = Niacin (Vitamin B3). Pakistan's EPI includes Vitamin A supplementation — a core community nursing intervention.