Vitamin A deficiency
（重定向自Phrynoderma）
![Disability-adjusted life year for vitamin A deficiency per 100,000 inhabitants in 2002.[27]
no data
less than 35
35–70
70–105
105–140
140–175
175–210
210–245
245–280
280–315
315–350
350–400
more than 400](/uploads/202502/02/Vitamin_A_deficiency_world_map_-_DALY_-_WHO2002.svg0953.png)
Vitamin A deficiency (VAD) is a lack of vitamin A in humans. It is common in poorer countries but rarely seen in more developed countries. Nyctalopia (night blindness) is one of the first signs of VAD. Xerophthalmia, keratomalacia, and complete blindness can also occur since Vitamin A has a major role in phototransduction.