Visual characteristics of elderly night drivers in the Salisbury Eye Evaluation Driving Study

PURPOSE. To characterize visual factors among those who continue to drive and those who restrict night driving in the elderly population. METHODS. The Salisbury Eye Evaluation Driving Study (SEEDS) is a study of vision, cognition, and driving behaviors of older drivers living in the greater Salisbury, Maryland, metropolitan area. Patients were recruited from listings in the Department of Motor Vehicle Administration. Data are reported from two visits conducted 2 years apart. Night driving was assessed using a real-time driving assessment tool, the Driving Monitor System. Night driving was defined by the presence of at least one episode of driving at night during a 5-day time period (seasonally adjusted). Participants also underwent a battery of cognitive and visual function testing including distance acuity, contrast sensitivity, and visual fields. Logistic regression was used to model factors associated with night driving. RESULTS. Complete data were available for 990 of the 1080 participants (92%) attending both visits; 41% of participants were driving at night in each visit. Those who were younger (P < 0.001), male (P < 0.001), and had better measures of cognitive (P 1/4 0.007) and visual function were observed driving at night, whereas those who were older, female, and had poorer measures of cognitive and visual function restricted their night driving behavior. An association was observed between depressive symptoms and less night driving in females (P 1/4 0.003). In multivariate analysis, better contrast sensitivity (odds ratio [OR] 1.18, 95% confidence interval [CI] 1.02-1.36, P 1/4 0.02) and visual field detection (OR 1.21, 95% CI 1.00-1.47, P 1/4 0.05) were associated with driving at night. Visual acuity was not found to be significantly related to night driving (OR 1.08, 95% CI 0.95-1.18, P 1/4 0.12). CONCLUSIONS. Restricting driving at night is a multifactorial behavior that has a vision component, notably poor contrast sensitivity, and some loss of visual fields.