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Purpose: To evaluate the on-road driving performance of persons with homonymous hemianopia or quadrantanopia in comparison to age-matched controls with normal visual fields. Methods: Participants were 22 hemianopes and eight quadrantanopes (mean age 53 years) and 30 persons with normal visual fields (mean age 52 years) and were either current drivers or aiming to resume driving. All participants completed a battery of tests of vision (ETDRS visual acuity, Pelli-Robson letter contrast sensitivity, Humphrey visual fields), cognitive tests (trials A and B, Mini Mental State Examination, Digit Symbol Substitution) and an on-road driving assessment. Driving performance was assessed in a dual-brake vehicle with safety monitored by a certified driving rehabilitation specialist. Backseat evaluators masked to the clinical characteristics of participants independently rated driving performance along a 22.7 kilometre route involving urban and interstate driving. Results: Seventy-three per cent of the hemianopes, 88 per cent of quadrantanopes and all of the drivers with normal fields received safe driving ratings. Those hemianopic and quadrantanopic drivers rated as unsafe tended to have problems with maintaining appropriate lane position, steering steadiness and gap judgment compared to controls. Unsafe driving was associated with slower visual processing speed and impairments in contrast sensitivity, visual field sensitivity and executive function. Conclusions: Our findings suggest that some drivers with hemianopia or quadrantanopia are capable of safe driving performance, when compared to those of the same age with normal visual fields. This finding has important implications for the assessment of fitness to drive in this population.

PURPOSE: This study was designed to examine the on-road driving performance of drivers with hemianopia and quadrantanopia compared with age-matched controls. METHODS. Participants included persons with hemianopia or quadrantanopia and those with normal visual fields. Visual and cognitive function tests were administered, including confirmation of hemianopia and quadrantanopia through visual field testing. Driving performance was assessed using a dual-brake vehicle and monitored by a certified driving rehabilitation specialist. The route was 14.1 miles of city and interstate driving. Two “back-seat” evaluators masked to drivers’ clinical characteristics independently assessed driving performance using a standard scoring system.--- RESULTS: Participants were 22 persons with hemianopia and 8 with quadrantanopia (mean age, 53 20 years) and 30 participants with normal fields (mean age, 52 19 years). Inter-rater agreement for back-seat evaluators was 96%. All drivers with normal fields were rated as safe to drive, while 73% (16/22) of hemianopic and 88% (7/8) of quadrantanopic drivers received safe ratings. Drivers with hemianopia or quadrantanopia who displayed on-road performance problems tended to have difficulty with lane position, steering steadiness, and gap judgment compared to controls. Clinical characteristics associated with unsafe driving were slowed visual processing speed, reduced contrast sensitivity and visual field sensitivity.--- CONCLUSIONS: Some drivers with hemianopia or quadrantanopia are fit to drive compared with age-matched control drivers. Results call into question the fairness of governmental policies that categorically deny licensure to persons with hemianopia or quadrantanopia without the opportunity for on-road evaluation.