Effect of ascorbic acid, vitamin B and milk on the dark adaptation.

The validity of the dark adaptation test for showing mild degree of a deficiency of vitamin A is now generally acknowledged. Thus Harris and Abbasy') found that impaired dark adaptation was common in children whose diet was estimated to be low in vitamin A while it was rare in well nourished children. There are, however, many contradictory reports2 3) concerning the effect of vitamin A on the dark adaptation. Among the subjects who developed delayed dark adaptation, some were completely cured within a few hours after receiving the vitamin, whereas others, though showing some immediate improvement, failed to return to normal after having gone through many months on vitamin A supplementation. The importance of vitamins other than vitamin A, for dark adaptation is uncertain, but the works of Harris et al.') and of Stewart4) suggest that ascorbic acid is important. This, however, is very definitely denied by Yudkin.5) Nicotinic acid, an essential ingredient of the visual purple cycle, has been reported by Hosoya et al.6) to be of clinical importance in dark adaptation. Following the administration of nicotinic acid to 3 subjects with poor dark adaptation they found that only one of them showed measurable improvement. A paper of Kimble and Gordon7) stressed as well the value of riboflavin. They observed that in a few patients who had both poor dark adaptation and a low blood vitamin A, large doses of vitamin A had no effect on either until riboflavin was given, when both became normal. But in some other individuals in whom riboflavin failed to produce this result, ascorbic acid caused satisfactory improvement. The divergent effect of the vitamins on the recovery of delayed dark adaptation stimulated the reexamination of them. The present study was designed to determine whether supplements of ascorbic acid, B vitamins and milk to the diet together or separately with vitamin A would have any advantages