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J. M. Wood, J. Elgin, G. McGwin, Jr., G. C. Meek, M. S. Vaphiades, R. A. Braswell, D. K. DeCarlo, L. B. Kline, D. A. Brenner, C. Owsley; On-Road Driving Performance by Persons With Hemianopia and Quadrantanopia. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3155.
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Many governmental jurisdictions around the world prohibit persons with hemianopia or quadrantanopia from obtaining a driver’s license. Since there has been little research on the actual on-road driving performance of these persons, we evaluated their on-road driving and compared it to an age-matched group of drivers with normal visual fields.
Persons with hemianopia and quadrantanopia were recruited from the UAB Neuro-ophthalmology service and the Comprehensive Stroke Research Center. Inclusion criteria were ≥ 6 months from the brain injury date and a current driver, or if not a current driver, interest in returning to driving. A battery of visual and cognitive tests were administered including verification of hemianopia and quadrantanopia. On-road driving performance was assessed in a dual-brake vehicle on a 14-mile course in Birmingham, AL that included non-interstate city driving and interstate driving. Performance was rated on a 5-point scale by two "backseat" raters who rated > 40 specific driving maneuvers with respect to 8 behaviors (e.g., lane position, speed, obey signals). They were masked to whether the driver had hemianopia/quadrantanopia versus normal visual fields.
The sample comprised 22 hemianopes and 8 quadrantanopes (M age 53 yrs), along with 30 persons with normal visual fields (M age 52). Inter-rater agreement was high (.96). All drivers with normal visual fields received ratings in the safe range. 73% of hemianopic and 88% of quadrantanopic drivers received safe ratings. Problem areas for hemianopic and quadrantanopic drivers rated as unsafe were lane position, steer steadiness, and speed. Among hemianopic and quadrantanopic drivers, clinical characteristics associated with unsafe driving included an absence of macular sparing and slowed visual processing speed.
This study demonstrates that some drivers with hemianopia or quadrantanopia are fit to drive, when compared against drivers of the same age who have normal visual fields. These 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.
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