Ophthalmologist emphasizes care in dim-light driving as time change brings darkness to evening commute

Beginning the week of Sunday, Nov. 6, when dusk arrives an hour earlier, many evening commuters will be on the road heading home in an after-dark rush hour.

According to the National Safety Council, traffic fatalities are three times higher at night than during the day, and coupled with the fact that Tennessee's mild weather conditions allow for continued outdoor activity, Amy Chomsky, M.D., associate professor of Ophthalmology and Visual Sciences at Vanderbilt University Medical Center, says both pedestrians and drivers need to be more alert to their surroundings.

The human eye functions differently in decreasing light, she says.

"We are not made like nocturnal animals," Chomsky says. "In dim light situations the rods in our retinas take over. They don't distinguish color and are not as sharp. Our pupils dilate so that more light can come into the retina. Although this is to help us see better at night, it also opens us up to more optical aberrations."

"People with baseline visual issues like cataracts, severe dry eyes or early macular degeneration will have more glare in dimmer conditions affecting the quality of their vision, and some people may even become more nearsighted at night because the pupils dilate," she said. "It is not uncommon for those having trouble driving at night to use prescription glasses for nighttime driving.

"The overall symptoms that people experience at night -- their contrast sensitivity goes down, the glare goes up and their pupils dilate really wide. Cataracts or dry eyes only exacerbate the issue."

She suggests that drivers train themselves to avoid looking directly into incoming headlights. If someone is having extreme difficulty with night vision, Chomsky recommends that he or she see an eye care professional.