Effect of visual impairment on driving.

The aim of the study was to determine the effect on driving of restricting vision. This was undertaken by comparing the driving performance of young, normal subjects under conditions of simulated visual impairment with a baseline condition. Visual impairment was simulated using goggles designed to replicate the effects of cataracts, binocular visual field restriction, and monocular vision. All subjects had binocular visual acuity greater than 6/12 when wearing the goggles and thus satisfied the visual requirements for a driver's license. Driving performance was assessed on a closed-road circuit for a series of driving tasks including peripheral awareness, maneuvering, reversing, reaction time, speed estimation, road position, and time to complete the course. Simulated cataract resulted in the greatest detriment to driving performance, followed by binocular visual field restriction. The monocular condition did not significantly affect driving performance for any of the driving tasks assessed.