Effect of Atropine on Dark Adaptation

¹ From the Applied Physiology Branch, Chemical Warfare Laboratories, Directorate of Medical Research, Army Chemical Center, Maryland

The Hecht-Shlaer adaptometer was employed to measure the course and threshold of dark adaptation following pre-exposure to 1740-ml intensity for 2 minutes' duration. Eight subjects in the first experiment were given four practice trials prior to their injection with either 2 mg/ml atropine sulfate intramuscularly or 1 ml physiological saline. Statistical analyses were then carried out to determine the effect of atropine on the course of dark adaptation and the effect of practice on the final threshold values. In the second experiment four subjects were employed to determine the effect of atropine on the final threshold values. The main results of the experiments were as follows: a) no significant change in final absolute threshold or the course of dark adaptation was occasioned by a 2-mg intramuscular injection of atropine sulfate; b) practice significantly reduced the dark adaptation threshold and the course of dark adaptation.