Abstract
Purpose :
Driving is a highly visual task. Understanding which aspects of visual sensory function and visual processing are associated with crash involvement may be useful for identifying high risk drivers. The purpose of this study is to estimate the magnitude of risk for crash involvement associated with impaired visual acuity, contrast sensitivity, driving visual field, visual processing speed, and visuospatial ability in a large, prospective study among older drivers.
Methods :
Visual acuity, contrast sensitivity, driving visual field sensitivity, UFOV (subtest 2), Trails B, and Spatial Closure Subtest of the MVPT were assessed at baseline in a population-based sample of 2000 licensed drivers aged ≥70 years from north central Alabama. Information on MVC involvement occurring 3 years after enrollment was obtained from the Alabama Department of Public Safety. At-fault status was determined by the police officer who arrived on the scene. Clinically meaningful cut-points were used to define impairment for each measure of visual function. Poisson regression models were used to calculate rate ratios (RR) and 95% confidence intervals (CI) of any and at-fault MVC involvement for each visual function. Models accounted for person-miles of travel and were adjusted for age, gender, race, MMSE, and number of medical conditions.
Results :
There were 223 drivers with 1 crash; 26 had ≥2 crashes during follow-up. The rate of any and at-fault MVC involvement was 6.00 and 3.00 per million miles traveled. After adjustment, rates of any MVC involvement were significantly higher for older drivers with impairment on the UFOV (RR 1.85, 95% 1.30-2.63), in the driving visual field (RR 1.34, 95% CI 1.02-1.76), and Trails B (RR 1.30, 95% CI 1.00-1.67). All of the visual impairment measures demonstrated positive associations with at-fault MVCs; however, rates were significantly higher for those with impairment on the UFOV (RR 1.88, 95% CI 1.16-3.04) and driving visual field (RR 1.59, 95% CI 1.10-2.32).
Conclusions :
In a population-based sample, slowed visual processing speed and impairment in the driving visual field demonstrated the strongest associations with at-fault MVC occurrence and can be used to identify older drivers at increased risk for an at-fault MVC. Healthcare providers and caregivers should discuss the risk of MVC involvement with older drivers with visual function impairment.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.