Abstract
Purpose :
To examine the association between visual impairment and driving performance at left turns at four-way intersections with traffic control among drivers aged ≥70.
Methods :
A 6-month prospective cohort study focused on drivers aged ≥70 years with eye conditions which could cause impairment using naturalistic driving methods was completed. After enrollment, participants completed a battery of visual and visual-cognitive function assessments including visual acuity, contrast sensitivity, visual field sensitivity, visual processing speed, and motion perception. To objectively collect driving information, a data acquisition system (DAS) was installed in participant vehicles. The DAS recorded continuous data streams from accelerometers, vehicle network, GPS, and 5-channel video camera system. Left turns were identified using accelerometer and GPS data and mapped to identify the location. To obtain 500 turns for data reduction, turns were randomized by participant and the location assessed to choose the first 3 or 4 turns for each participant occurring at a four-way intersection with traffic control. Trained analysts coded two outcomes: safe versus unsafe traversal and normal versus improper turn behavior. Generalized estimating equations, which account for repeated measures, were used to calculate age-adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) for the outcomes and association with visual impairment.
Results :
A total of 473 left turns were assessed among 151 participants. Impaired visual processing speed (Trails B) was associated with 46% reduced odds of unsafe traversal (OR: 0.54, 95% CI: 0.34-0.85). Visual field sensitivities (overall, peripheral, lower, left) were significantly associated with 42-44% reduced odds of unsafe traversal. Similar significant protective associations were seen for those with impaired contrast sensitivity, visual processing speed (Trails B), and visual field sensitivities (peripheral, upper, lower, left) and improper turn behavior.
Conclusions :
Older adults with vision impairment had reduced odds of unsafe traversal and improper behavior. While this finding could seem counterintuitive, it is consistent with self-report literature indicating that older drivers are aware of challenging driving situations and therefore could be more cautious. As this is the first examination of these associations, future work should further explore these findings continuing to use objective means.
This is a 2021 ARVO Annual Meeting abstract.