Effect of Caffeine and Bromide on Dark Adaptation

Abstract

DURING the past two years we have been making an investigation of dark adaptation of the central region of the retina with special reference to the recovery occurring during the first minute after the end of light adaptation. The work has included some experiments on the effect of doses of potassium bromide and of caffeine on the subject. With doses of potassium bromide up to 25 grains no effect on the rate of adaptation or on the scatter of the observations was observed. With one subject who was used to drinking strong coffee and tea frequently no effect was produced with a dose of 8 grains of caffeine. With another subject whose consumption of tea and coffee may be regarded as at least average, a definite, though rather small, increase in the rate of adaptation was noted when doses of caffeine of up to ten grains were given. The increase was appreciable with 6 grains. In view of these results it is not surprising that at no time were we able to observe any effect due to fatigue or to minor ill-health.