The effect of simulated visual impairment on the driving performance of 14 young and 10 old normal subjects was investigated. Visual impairment was induced using goggles to simulate the effects of cataracts, visual field restriction and monocular vision. Driving performance was assessed on a closed-road circuit free of other vehicles. Visual performance was assessed using Divided Attention Visual Fields (DAVF), Useful Field of View (UFOV) and the Pelli-Robson letter contrast sensitivity (CS) chart. Visual impairment significantly reduced performance for all driving tasks (p<0.05). Cataracts resulted in the greatest decrease in driving followed by visual field restriction, even though all drivers satisfied the visual requirements for driving. Monocularity did not significantly affect performance for any of the driving tasks assessed. The reduction in driving performance was greater for the old subjects. Visual impairment significantly decreased the DAVF, UFOV and Pelli-Robson letter CS (p<0.05). A significant correlation between driving and DAVF, UFOV and Pelli-Robson letter CS was demonstrated (p<0.05). Ongoing studies of a large group of subjects with true visual impairment are being undertaken. Preliminary data supports the finding that visual impairment can reduce driving performance, even when the visual requirements for driving are satisfied. (A)
Samenvatting