Visual functions associated with on-road performance by older drivers evaluated by a certified driving rehabilitation...

To assess associations between visual function and on-road driving performance evaluated by a certified driving rehabilitation specialist (CDRS).

Adults aged 70 and older enrolled and completed assessments of visual acuity, contrast sensitivity, visual processing speed, visual field sensitivity, motion perception and spatial ability. At follow-up, on-road driving performance was evaluated on a 15-mile route. Age-adjusted odds ratios and 95% confidence intervals (95% CIs) were used to associate worse CDRS composite score and CDRS global rating for those with poorer visual function compared to those with better scores and ratings.

For the 144 participants who enrolled, completed vision testing and the on-road driving evaluation, the mean age was 79.2 (5.1) and 45.8% were female. The odds of worse CDRS global rating and composite score were significantly associated with moderately and severely impaired visual processing speed under divided attention (all p < 0.05). Those with poorer motion perception were at greater odds of a worse CDRS composite score (OR: 2.67, 95% CI: 1.14-6.26).

The CDRS composite score of on-road driving performance by older adults was associated with slowed visual processing and impaired motion perception, suggesting that older driver performance, as rated by a CDRS, relies on visual skills. The CDRS global rating was also associated with impaired visual processing speed. The literature suggests impairments in these same visual functions elevate crash risk. While the results provide additional evidence suggesting these functional measures are associated with driving, further work is needed to identify and assess visual measures most closely related to driving safety and performance among older adults to better inform interventions, policy and future research.