Scanning behaviour and daytime driving performance of older adults with glaucoma

Purpose: To assess the visual scanning behaviour and closed-road driving performance of older drivers with glaucomatous visual impairment. Method: Participants included 13 older drivers with glaucomatous visual impairment (mean age=72±7 years; average better-eye mean deviation (MD)=−3±2 dB, average worse-eye MD=−13±7 dB) and ten visually-normal controls (mean age=71±7 years). Visual acuity, contrast sensitivity, visual fields, useful field of view (UFoV), and motion sensitivity were assessed. Participants drove around a closed-road circuit while their eye movements were recorded with an ASL Mobile Eye-XG. Driving performance measures included hazard avoidance, sign recognition, and lane-crossing time; overall driving z-score was derived from these three component measures. Results: Glaucoma participants had significantly poorer overall driving scores than the controls (0.1 vs 0.4; p=0.018) and hit almost twice the number of hazards compared to controls (24% vs 13%; p=0.043). The glaucoma group also exhibited larger saccade amplitudes (p<0.001), horizontal (p<0.001) and vertical search variances (p=0.002) than controls. Larger saccades were associated with better overall driving scores in the glaucoma group (p=0.001), but not the controls (p=0.65). Across all participants, the strongest visual predictor of overall driving score was better-eye MD (p<0.001), followed by binocular Esterman, integrated visual fields, worse-eye MD, dot motion sensitivity, contrast sensitivity, and the UFoV subtest 2 (p<0.05). Conclusion: Drivers with glaucoma had poorer driving performance than the controls and demonstrated differences in eye movement patterns, where larger saccades were associated with better driving scores. These findings suggest that altered scanning behaviours may benefit driving performance and safety in drivers with glaucoma.