Question

Which of the following vitamins at higher doses causes cystoid macular edema?

• A. Vitamin A
• B. Vitamin D
• C. Vitamin E
• D. Niacin

Hint:

Think of the lipid-lowering vitamin given in gram doses.

Answer 1

The Correct Option is D

Clinical-pearl approach: the buzzword pairing here is high-dose niacin and cystoid macular edema. Niacin (nicotinic acid, vitamin B3) is prescribed in gram-level doses to treat dyslipidemia, and at roughly 3 g per day or more it produces a characteristic ocular toxicity that includes cystoid macular edema, blurred vision, and eyelid edema. The classic exam point is that this niacin maculopathy is non-leaking on fluorescein angiography (unlike most causes of macular edema) and fully reverses when the drug is withdrawn. That makes option (d) the answer. Eliminate the fat-soluble vitamins by their own toxicity signatures: vitamin A excess gives raised intracranial pressure and papilledema, vitamin D excess gives hypercalcemia and band keratopathy, and vitamin E excess interferes with clotting. None of these produce cystoid macular edema, so niacin stands alone.