Dark Adaptometer Readings of Subjects on a Diet Deficient in Vitamin A

In this paper some observations on the dark adaptation of 2 subjects on a diet low in vitamin A are described, and their bearing on the use of the dark adaptometer of Hecht and Shlaer1as an instrument for the detection of vitamin A deficiency is discussed. This instrument is one of the most promising of those developed in the attempt to find a measure of visual dysadaptation which will serve as a reliable indicator of the state of vitamin A nutrition (compare the introduction of a paper written by Caveness, Satterfield and one of us [Dann]).2It meets certain specifications which are enumerated in that paper as essential for measurement of visual thresholds during the course of light and dark adaptation and which have not been met in earlier instruments. With the new dark adaptometer Hecht and Mandelbaum3have examined a group of suitable subjects to