Purpose: We designed a visual field test focused on the field utilized while driving to examine associations between field impairment and motor vehicle collision involvement in 2000 drivers aged 70 years or older.
Methods: The "driving visual field test" involved measuring light sensitivity for 20 targets in each eye, extending 15° superiorly, 30° inferiorly, 60° temporally, and 30° nasally. The target locations were selected on the basis that they fell within the field region utilized when viewing through the windshield of a vehicle or viewing the dashboard while driving. Monocular fields were combined into a binocular field based on the more sensitive point from each eye. Severe impairment in the overall field or a region was defined as average sensitivity in the lowest quartile of sensitivity. At-fault collision involvement for 5 years prior to enrollment was obtained from state records. Poisson regression was used to calculate crude and adjusted rate ratios (RRs) examining the association between field impairment and at-fault collision involvement.
Results: Drivers with severe binocular field impairment in the overall driving visual field had a 40% increased rate of at-fault collision involvement (RR, 1.40; 95% confidence interval [CI]: 1.07-1.83). Impairment in the lower and left fields was associated with elevated collision rates (RR, 1.40; 95% CI: 1.07-1.82 and RR, 1.49; 95% CI: 1.15-1.92, respectively), whereas impairment in the upper and right field regions was not.
Conclusions: Results suggest that older drivers with severe impairment in the lower or left region of the driving visual field are more likely to have a history of at-fault collision involvement.
Keywords: aging; driving; visual field.
Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.