Does it sometimes feel like you are wearing sunglasses when driving at low light or in the night time? Do you find yourself humming the Corey Hart song from 1984, “Sunglasses at Night?” Though presented as ultra-cool in some movies and music videos, as some people’s eyesight begins to degrade, they might well be living the song title.
Problems with night vision are linked to a higher likelihood of traffic accidents and fatalities; both driver and pedestrian can be contributing with poor vision. And good daytime vision does not automatically translate to good low-light eyesight. Indeed, because some vision problems develop so slowly, many people will not realize their vision is declining until it has seriously degraded.
Problems with low-light vision are part of the aging process. As we get older our pupils get smaller and let less light into the retina. We also experience a reduction in the number of rods in the retina meaning a decrease in the ability to see contrast: objects are less distinct or blend into their background. This could mean not seeing a pedestrian or obstacle on the road. Aging retinas start to lose the ability to quickly recover from bright to dark, for example after facing an oncoming vehicle.
Aging corneas and lenses can also be less clear (cataracts) thus causing light to scatter inside the eye and increasing glare. Aging is not the only culprit for declining night vision. Problems may also arise for people with diabetes or dry eye syndrome, and after LASIK or similar eye surgery.
One way to improve our safety on the roads at night is to make infrastructure changes: better road lighting, more and better reflectors and paint on the roads (have you seen how brightly those new reflectors are?!) and adding rumble strips on the shoulder. Vehicles are also getting improvements including new headlights which produce much more, cleaner light.
And on some luxury vehicles we are seeing ‘night-vision systems’ which can ‘see’ pedestrians and animals using infrared cameras.
It may be hard to know if your night vision is becoming less effective. Indeed, since most eye exams take place under daylight conditions, even an eye test might not be enough. If you have any concerns about declining night vision, talk to your eye care professional who can test for it. You may be offered night driving glasses if there is a problem, even if you don’t wear glasses during the day.
There are steps to take which can improve your safety and that of others on the road with you. These suggestions work even if you still have good night vision. Start by making sure windows, headlights and mirrors are clean and that windshield wipers work well. When driving, slow down and maintain extra space margins; don’t overdrive your headlights. As a pedestrian or cyclist, wear light clothing, or better yet, reflective gear and walk facing oncoming traffic.
Because eye problems can decline so gradually, you might not realize that you have become visually impaired. If you have any doubt about your night vision, limit yourself to daytime driving and arrange for an eye exam. It could save more than one life.
Written by Dr. Paul Martiquet, Medical Health Officer for Rural Vancouver Coastal Health including Powell River, the Sunshine Coast, Sea-to-Sky, Bella Bella and Bella Coola.