Measures of visual function and their association with driving modification in older adults

PURPOSE. Older drivers may place restrictions on their driving by reducing their mileage and avoiding high-risk driving situations in an effort to improve safety. This project identifies what types of visual function loss are associated with subsequent driving modifications. METHODS. Data were used from the baseline and 2-year follow-up rounds of the Salisbury Eye Evaluation project, a cohort study of 2520 older adults. Measures of visual function tested were visual acuity, contrast sensitivity, visual fields, and glare sensitivity. Driving information was self-reported. Among drivers at baseline who continued to drive at follow-up, multiple logistic regression was used to estimate the odds of incident driving modification by visual function status. RESULTS. Worse baseline scores in acuity, contrast sensitivity, and central and lower peripheral visual fields were individually associated with an increased odds of reduced mileage 2 years later (linear trend P < 0.05). Worse baseline scores in contrast sensitivity and central and lower peripheral visual fields were individually associated with a greater odds of cessation of night driving 2 years later, whereas worse baseline acuity scores were associated with an increased odds of cessation of driving in an unfamiliar areas 2 years later (linear trend P < 0.05). CONCLUSIONS. Older drivers with worse visual function were more likely to modify their driving by reducing mileage and avoiding high-risk driving situations. Furthermore, these modifications to driving differed depending on what type of visual function was affected.