Duh:Difficulty Seeing Means Trouble Driving
November 12, 2009 by Marijke Durning, RN
Filed under Duh Studies
Really? Let’s file this one in the Duh Files: If you’re blind in one half of each eye, such as the right side of each eye (called hemianopia), you likely will have more trouble seeing pedestrians in your “blind” spot. Seriously. Hemianopia is usually caused by a brain injury, such as a stroke, tumor or trauma.
Researchers from Schepens Eye Research Institute performed a small study (24 people) to see how hemianopia affected driving. Their results were published in the most recent issue of Investigative Ophthalmology and Visual Science.
According to a press release from the institute,
More than a million people suffer from hemianopia, a condition in which one half of the visual field in both eyes is blinded, usually the result of a stroke or head injury. People with hemianopia often do not know what they can’t see and frequently bump into and trip over objects while walking. Driving is a whole other challenge.
As a result, at least 22 states in the United States don’t allow people with this disorder to drive, as do many other countries.
For the study, researchers took 12 people with hemianopia and 12 people without. The two groups were tested on a driving simulator for 2 hours. Their test drive took them along city roads and rural highways. To test their reflexes, “pedestrians” randomly appeared out of nowhere. The drivers were to honk each time they saw a pedestrian.
Not surprisingly, drivers with hemianopia did not see the pedestrians as often as the control group, without the the visual problem – only about 45% of the time. Again, not surprisingly, they had the most difficulty seeing the pedestrians who appeared on the drivers’ blind sides. However, this did vary considerably, from 6% to 100%. The older the driver, the worse the results.
Now, this was a very small study and small studies have their problems, but I did find this quote from the press release a bit puzzling:
Although overall most subjects with hemianopia had detection rates that seem incompatible with safe driving, [Dr. Eli] Bowers [principal investigator of the study and senior scientist at Schepens Eye Research Institute] cautions that “the relationship of our simulator detection performance measures to on-road performance has yet to be established, another reason to treat each person with hemianopia individually as they seek approval to get back on the road.”
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Image: PhotoXpress.com
