Effect of Administration of Thyroid Extract and of α-Dinitrophenol upon Dark Adaptation

Abstract

Previous studies 1 , 2 have shown that the process of dark adaptation of the eye may be disturbed in certain patients having cirrhosis of the liver or renal stone. The abnormal dark adaptation was characterized by (a) elevation of the cone and rod thresholds, (b) reduction in the speed of the process, or (c) a combination of these two effects. Other studies 2 , 3 have shown that simple Vitamin A deficiency, as from diets deficient in the vitamin or from obstructive jaundice, may produce threshold changes alone. However, the reduction in speed of adaptation appeared to be a different phenomenon. Since this latter change, like the elevated visual thesholds, responded favorably to Vitamin A therapy, the delay in adaptation was interpreted as possibly a manifestation of faulty utilization of the vitamin.

Attention, therefore, was directed to other factors which might influence the speed of dark adaptation and which thus might be involved in the intermediary metabolism of Vitamin A. The method and apparatus for measuring dark adaptation was similar to that previously employed. 2 Serum Vitamin A and carotenoids were determined by a modification of the method described by Kimble. 4 The usual hospital diet without Vitamin A concentrates was fed throughout the period of observations.

The oral administration of thyroid extract or of α-dinitrophenol to 3 patients with markedly prolonged dark adaptation produced sharp changes in both rod and cone functions. The effect of thyroid extract was tested 4 times in 3 patients, whereas the effect of α-dinitrophenol was tested 2 times in 1 of these patients.

Table I records values for dark adaptation and for serum Vitamin A and carotenoids in these 3 patients.