BOSTON — People with central vision defects who wear bioptic telescopic glasses for driving tend to limit their car use to short or necessary trips, according to a study of 74 users licensed to drive in Ohio.
"We found that across the board, everyone seems to be using their bioptics and driving for the same number of trips," said Ellen Segerstrom, OD, from the Ohio State University College of Optometry in Columbus.
However, older people, those with decreased vision, and those with decreased contrast sensitivity "were limiting themselves to locations closer to home," she reported here at Optometry's Meeting by the American Optometric Association.
"In the near future, we're hoping to be able to use this information on driving exposure — how far, how long, how many miles driven per year — to calculate crash risk and to get a better look at which patients are safe on the road and how to better keep our bioptic drivers safe and crash-free," Dr Segerstrom told Medscape Medical News.
Bioptic users can be licensed to drive in 43 states, with varying degrees of restriction. The ability to drive is key to the independence of people with central vision defects, particularly older drivers.
Most States Allow Bioptics
"We previously found that age and visual acuity do not predict the number of collisions per year. However, that analysis did not account for miles driven per year," Dr Segerstrom and colleagues explain in their scientific poster.
The study participants had been licensed for an average of 11 years and drove a median of 7000 miles annually. They completed a modified form of the Driving Habits Questionnaire, which asked them to estimate miles driven weekly and annually and to report destinations. Age of participants at initial licensure, visual acuity, and contrast sensitivity were obtained from clinical records.
Median age of the study cohort was 51 years, median binocular logMAR visual acuity was 0.70 (20/100), and median log contrast sensitivity was 1.65 (near normal).
Spearman's correlations showed that increasing age (rho, –0.28; P = .18), poorer visual acuity (rho, –0.25; P = .03), and poorer contrast sensitivity (rho, 0.42) were inversely correlated with the farthest distance traveled, indicating that those with the lowest vision tended to stick closer to home.
There was no correlation between the number of weekly car trips and age, vision, or contrast sensitivity. In addition, there was no association between years of licensure and any measure of driving exposure.
"These data indicate that, while older bioptic drivers and those with poorer vision may alter their driving habits with regard to distance, bioptic licensure may still be useful for completing valued activities," Dr Segerstrom and her colleagues write.
Bioptic telescopes are an important lifeline for some people with central vision defects, said Thomas Azman, OD, from the Department of Ophthalmology at the University of Maryland in College Park, who was not involved in the study.
"Patients were driving anyway, with their current glasses, before they got bioptics," he told Medscape Medical News. "Now they're seeing better and I have not heard of any increased incidence of accidents among them."
Dr Azman said he only prescribes bioptics when he is confident that they can be used safely and correctly.
"I made one for myself; I'm not a low-vision patient, but I wanted to see how it works," he reported. "It's awesome."
This study was supported by the National Institutes of Health and Prevent Blindness Ohio. Dr Segerstrom and Dr Azman have disclosed no relevant financial relationships.
Optometry's Meeting by the American Optometric Association (AOA): Poster 29. Presented July 2, 2016.
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Cite this: Drivers Wearing Telescopic Glasses Seem to Know Their Limits - Medscape - Jul 05, 2016.