Left Turns by Older Drivers With Vision Impairment: A Naturalistic Driving Study

Abstract

Background and Objectives Older drivers are over-represented in collisions at intersections while making left turns across oncoming traffic. Using naturalistic driving methods, we evaluated the association between vision impairment and their left turn characteristics. Research Design and Methods In this prospective, observational study, vision impairment as defined by visual acuity, contrast sensitivity, visual processing speed, visual field sensitivity and motion perception was assessed in drivers ≥70 years old. Data acquisition systems were installed in their personal vehicles recording video and vehicle kinematics. Driving during everyday life was recorded for six months. Data analysts evaluated a temporal data window surrounding randomly selected left turns at four-way intersections. Left turn traversals and turning behavior were evaluated in terms of age-adjusted associations with vision impairment. Results The sample consisted of 151 older drivers. The number of turns studied was 473; 265 turns were rated as unsafe traversals, and 201 as problematic turning behavior. Drivers with slowed visual processing speed and visual field impairment were less likely to exhibit unsafe traversals (p< 0.05); those with worse contrast sensitivity, slowed visual processing speed, and visual field impairment were less likely to exhibit problematic turning behavior (p <0.05). Discussion and Implications Using naturalistic driving, our study suggests older drivers with vision impairment exhibit better performance in making left turns than those without deficits, which contradicts older driver studies on left turns using driving simulators and on-road driving evaluations. Our findings suggest more cautious and self-regulatory behavior which are consistent with older visually impaired drivers’ commonly expressed concerns about their driving difficulties. Translational Significance In contrast to previous older driver studies using driving simulators and on-road driving evaluations, our study suggests that in everyday life older visually-impaired drivers exercise caution in left-turn behavior across oncoming traffic as compared to those who are normally sighted.

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