Automobile driving performance of brain-injured patients with visual fielddefects

The purpose of this study was to examine whether patients with visual field defects resulting from cerebral injury are handicapped in their driving ab ility, because visual field loss as assessed in standard perimetry is often the basis for withdrawal of a person's driving license. Driving performanc e was tested on a driving simulator to obtain standardized results and for safety reasons. The visual field was assessed both with standard automated perimetry and computer-based, high-resolution, qualitative perimetry. We in vestigated nine patients with purely cerebral field defects (mostly homonym ous binocular defects) who had no further neuropsychological or ophthalmolo gical deficits. Their performance (driving speed, reaction time, and drivin g error rate) was compared with that of a control group of ten subjects. We found no differences in any of the tested parameters between the visually impaired subjects and the normal participants. This suggests that individua ls with visual field defects, including those who suffer from homonymous he mianopia, may perform as adequately as normal individuals in realistic driv ing scenarios. The perimetrically assessed visual field may, thus, be of li mited value for the prediction of driving safety and we conclude that patie nts who have field defects should not summarily be denied a driving license .