A population-based examination of the visual and ophthalmological characteristics of licensed drivers aged 70 and older.

Background: Safe driving performance depends on visual skills yet little is known about the prevalence of vision impairments in older drivers and the eye conditions that cause them. This study is a population-based examination of the prevalence of vision impairment and major ophthalmological conditions among drivers aged 70 and older.
Methods: The source population was a random sample of 2,000 licensed drivers aged 70 and older residing in north central Alabama. All had driven within the past 3 months. Binocular visual acuity and contrast sensitivity were assessed. The Useful Field of View subtest 2 and Trails B assessed visual processing speed. Ophthalmological diagnoses for cataract, intraocular lens placement, glaucoma, diabetic retinopathy, age-related macular degeneration, and diabetic retinopathy were obtained through medical records from the most recent eye examination.
Results: Ninety-two percent of drivers had visual acuity of 20/40 or better; only two drivers (0.1%) had acuity worse than 20/100. Ninety-three percent had normal contrast sensitivity (≥1.5). About 40% had slowed visual processing speed (44%, Useful Field of View; 38%, Trails B). The most common eye condition was cataract, with more than half having cataract in one or both eyes (56%); yet by the 80s and 90s, the prevalence was low, with most drivers having undergone cataract surgery and intraocular lens placement.
Conclusions: This population-based study suggests that serious impairment in central vision-visual acuity or contrast sensitivity-is rather uncommon in older drivers; however, slowed visual processing speed is common.