Effects of oxazepam on eye movements and performance in vigilance tasks with static and dynamic stimuli.

The aim of the present study was to determine whether in a task with stimuli inducing frequent saccadic eye movements, ingestion of oxazepam impairs performance more than in a task in which the stimuli remained fixed at the same location, due to effects of oxazepam on the ocular system. Eighteen males performed a vigilance task with static and dynamic stimuli under the influence of oxazepam (20 and 40 mg) in a placebo-controlled, double blind, crossover design. Oxazepam (40 mg) had a larger effect on vigilance performance in the first part of the dynamic task, relative to its static counterpart. Oxazepam also had an effect on oculomotor behavior, but this effect was unrelated to impaired performance. There were dose-dependent effects of oxazepam on absolute, overall level of performance but not on the decrement with time. The non-dose-dependent aggravation of the decrement in correct detections, caused by the drug, could only partly be accounted for by pharmacokinetics and increased eyelid closures, and was also caused by pharmacodynamic effects of the drug, such as those on attention. Different effects were noted for the two signal detection measures of response behavior, B" and RI.