The night vision threshold test is a better predictor of low serum vitamin A concentration than self-reported night blindness in pregnant urban Nepalese women.
Taren DL, Duncan B, Shrestha K, Shrestha N, Genaro-Wolf D, Schleicher RL, Pfeiffer CM, Sowell AL, Greivenkamp J, Canfield L. The night vision threshold test is a better predictor of low serum vitamin A concentration than self-reported night blindness in pregnant urban Nepalese women. J Nutr. 2004 Oct; 134(10):2573-8.