VMD-0143
QUESTION
Nyctalopia and xerophthalmia seen in hypovitaminosis A is due to?
OPTIONS
(A) Regeneration of visual purple
(B) Degeneration of visual purple
(C) Increased CSF pressure
(D) Atrophy of epithelial cells
ANSWER
(B) Degeneration of visual purple
EXPLANATION
Nyctalopia in vitamin A deficiency results from impaired formation and regeneration of rhodopsin, or visual purple, in retinal rods; with deficiency, the pigment degenerates or cannot be maintained adequately. Increased CSF pressure and epithelial atrophy are other possible vitamin A effects but do not directly explain night blindness.
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