NUTRITIONAL NIGHT BLINDNESS

Night blindness, sometimes called hemeralopia or nyctalopia, which is a difficulty in adapting, or an inability to adapt, the faculty of vision to very faint illumination, may result from nutritional deficiency as well as from intra-ocular disease. It was recognized at the time of Hippocrates that liver or liver and honey was a cure for night blindness. In the past few years, experimental and clinical evidence have demonstrated that night blindness caused by faulty nutrition is the result of deficiency in vitamin A and is not infrequently the first manifest symptom of such deficiency. The most familiar form of deficiency of vitamin A, xerophthalmia, both of infants and of adults, especially the latter, is extremely rare in the United States. This is largely because vitamin A or its precursor, carotene, is widely available in foodstuffs, and the body ordinarily stores large quantities of this substance, a fact not true of