November 26, 2023

Early evening darkness brings dangers for drivers and pedestrians

The end of daylight saving time means many of us are driving home in the dark


At the end of daylight saving time and as we enter some of the shortest and darkest days of the year, ophthalmologists at the Vanderbilt Eye Institute want to focus on a real issue: dim-light driving situations that can endanger drivers and pedestrians.

When dusk arrives so much earlier, many evening commuters are on the road heading home in an after-dark rush hour.

“We are not made like nocturnal animals. In dim light situations the rods in our retinas take over. They don’t distinguish color and are not as sharp.”

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, said both pedestrians and drivers need to be more alert to their surroundings.

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

“We are not made like nocturnal animals,” Chomsky said. “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.

Photo: iStock