Older Drivers, Vision Screening, and Traffic Fatalities
Does screening older drivers' visual acuity translate to fewer traffic fatalities?
That's what Gerald McGwin's been trying to figure out. In two studies published this year, McGwin, of the School of Public Health at the University of Alabama at Birmingham, examined the impact of a 2004 Florida law requiring all drivers over 80 who apply to renew their driver's licenses -- including, for the first time, those who don't apply in person but by mail or online -- to pass a visual acuity screening test.
In the first study, which appeared in the March/April issue of Ophthalmic Epidemiology, McGwin reports that despite widespread concern in Florida that the new law would restrict older drivers' access to transportation and make it harder for them to get to the golf course, grocery store or doctor's office, in fact very few people over 80 were barred from driving by the screening. Most of those who failed the first time sought treatment and eventually passed. And the study found that some people opted not to pursue license renewal because they felt their vision wasn't good enough.
In the second study, published in the November issue of the Archives of Ophthalmology, McGwin found that, while traffic-related fatalities in general increased slightly (by 6 percent) in the couple of years after the law was implemented as compared to the couple of years before the law, traffic deaths among drivers 80 and older declined rather sharply (17 percent). In neighboring Alabama and Georgia, by comparison, where no such laws had been introduced, traffic fatality rates remained steady across the population.
This, despite the surprising fact that, as McGwin points out, there's scant scientific evidence supporting any link between visual acuity and involvement in motor vehicle accidents.
Visual acuity is one's "ability to see things sharply, straight in front of you," McGwin explains. "If you think of it, it's probably not all that critical for driving." Being able to track a moving object -- an ability not measured in the visual acuity assessment -- is more important, he says; peripheral vision is key to safe driving, too.
So, McGwin argues, while it appears that the vision screening law had a positive effect, nobody knows how or why.
"If you were in the department of public safety, you might say, 'We don't care why it works -- we just care that it works,'" McGwin notes. "But if you were someone in another state thinking about implementing a similar law and deciding how to allocate resources, you might want to better understand the mechanism. If screening itself isn't what caused the reduction, there's no sense spending resources" to implement a screening program, he says.
McWin's next project: a large study to determine "what is the best screening test for identifying unsafe older drivers." In the meantime, look here to learn about your state's vision screening requirements for seniors.
Any older drivers in your life? Do you worry about their safety on the road? And do you think their vision plays a role in their performance behind the wheel?
Posted by: JHBVA | November 14, 2008 9:27 AM | Report abuse
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