How providers assess vision in the first place may also need improvement. Nearly all providers test visual acuity, in which patients read smaller and smaller letters, and peripheral vision, but there is not strong evidence for how these tests relate to safe driving, Musch said.
Tests like contrast sensitivity could improve the assessment of safe driving, some say. The contrast test is similar to the visual acuity test except patients have to read letters that are gray, instead of black, on a white background.
Baker said he wishes doctors would test contrast sensitivity more often.
"You don't need to be able to read the license plate in front of you, you need to be able to tell if it's a car in front of you or a shadow or some other object," he said.
To learn more about driving safety, visit the U.S. National Highway Traffic Safety Administration.
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