A STUDY OF DIET IN RELATION TO HEALTH. DARK ADAPTATION AS AN INDEX OF ADEQUATE VITAMIN A INTAKE: III. The Relation of Diet to Rate and Extent of Dark Adaptation

Abstract

WHEN this investigation was started (March, 1938), there were three main methods in use for studying dark adaptation as an index of vitamin A intake. The modification of Edmund and Clemmesen's method described by Mutch and Griffith (1937) was being used at the Rowett Research Institute as part of the scheme for an extensive dietary and clinical survey. Meanwhile studies of dark adaptation with the Birch-Hirschfeld photometer had been published by Maitra and Harris (1937) with an estimate of frequency of subnormal dark vision in groups of school children. From America reports had appeared of investigations with the new patented modification of the latter photometer, the biophotometer (Jeans, Blanchard and Zentmire, 1937; Jehgers, 1937) and this method was also being used to assess the incidence of vitamin A deficiency in groups of the population. It appeared desirable, therefore, to determine whether the different methods copyright.