Scanning behaviour and daytime driving performance of older adults with glaucoma

Purpose To assess the link between visual scanning behaviour and closed-road driving performance in older drivers with glaucomatous visual impairment. Methods Participants included 13 older drivers with glaucoma (mean age=72.0±6.7 years; average better-eye mean deviation [MD])= −2.9±2.1dB, average worse-eye MD=−12.5±7.1dB) and ten visually-normal controls (mean age=70.6±7.4 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, and head movements recorded using the gyroscope sensors of a smart phone. Measures of driving performance included hazards hit, sign recognition, and lane-crossing time; an overall driving score was derived from these component measures. Results Participants with glaucoma had significantly poorer overall driving scores (p=0.026) and hit more hazards (p=0.043) than controls. The glaucoma group also exhibited larger saccades (p<0.001) and horizontal (p<0.001) and vertical search variances (p=0.002) than controls. Larger saccades were associated with better driving scores in the glaucoma group (p=0.001), but not the controls (p=0.75). Head movements did not differ between groups. For all participants, better-eye MD was the strongest visual predictor of overall driving score (p<0.001), followed by the other measures of visual fields, motion sensitivity, contrast sensitivity, and UFoV (p<0.05). Conclusion Older drivers with glaucoma had poorer driving performance than controls and demonstrated differences in eye movement patterns. The association between larger saccades and better driving scores in those with glaucoma suggests that altering scanning behaviour may benefit driving performance and safety in this group.