Effect of sarin on dark adaptation in man: threshold changes.

The Hecht-Shlaer adaptometer was used with an artificial pupil of 2 mm diameter to measure the course and absolute threshold of dark adaptation following pre-exposure to 3784 mL intensity for 2 minutes. Two subjects were given three familiarization trials prior to exposure to Sarin (isopropyl methylphosphono-fluoridate) in a specially constructed chamber. Following exposure, measurements were made at intervals of 1, 4 and 24 hours. Measurements of pupillary diameter and red blood cell cholinesterase inhibition were made prior to and after exposure. After total exposure to Sarin for 2 minutes at a concentration of 2.73 mg/m3, one subject manifested 23% RBC cholinesterare inhibition whereas a second subject, administered a total exposure of 2.02 mg/m3 for the same duration, showed no inhibition of cholinesterase activity. Following exposure to Sarin, pupillary constriction became manifest and remained constant over a 24-hour period within the limits of errors of measurement. The concentrations of Sarin empl...