How UV rays harm your eyes
Cumulative effects of exposure is big concern
The health message is clear: Wear sunglasses that offer protection from ultraviolet rays, the invisible radiation from sunlight. But what are the harmful effects on eyes from ultraviolet rays?
On a bright day, excessive exposure to sunlight reflected off sand, snow or water can damage the eye’s surface, much like a sunburn to the skin. But doctors are particularly concerned about cumulative effects of ultraviolet light exposure. Over the years, UV exposure contributes to the development of several eye disorders, including cataracts, a clouding of the lens.
“We’re seeing cataracts in younger people, in their 30s and 40s,” says Dr. Allan Slomovic, associate professor of ophthalmology at the University of Toronto. “Traditionally it’s a disease of people in their late 60s, 70s and 80s.” One theory is our eyes are under increased ultraviolet exposure from the depletion in the atmosphere’s ozone layer.
Pterygium, a vascularized fibrous growth in the white of the eye that extends onto the cornea, is more common in people exposed to excessive sun. “We’ve had people with significant vision loss from that,” says Slomovic.
UV exposure is also believed to contribute to age-related macular degeneration, a leading cause of blindness in Canada. The macula is the area on the retina, at the back of the eyeball, responsible for central vision.
“The ultraviolet rays cause the eye tissues to age more quickly than they normally would,” explains Dr. Ralph Chou, associate professor at the University of Waterloo’s School of Optometry and Vision Science.
Exposure early in life may set the stage for macular degeneration later on. A child’s eyes, up to about age 10, he explains, are clearer, more transparent to ultraviolet light, a strong argument for youngsters to wear sunglasses.
There’s some evidence that prolonged exposure to blue light, the visible light closest to ultraviolet on the wavelength spectrum, also damages the macula. “It all piles on,” says Chou. “Macular degeneration is the accumulation of all the effects over the decades.”
As an optometrist, he’s also seen precancerous lesions on patients’ eyelids and skin around the eyes, usually from too much sun. The skin near the eyes tends to be thin and vulnerable to damage. While these lesions can be cut away, he says, the result may be disfiguring.
Cancers associated with chronic ultraviolet exposure can also develop on the eye’s surface, says ophthalmologist Slomovic. There may also be a link between sun exposure and cancers inside the eye. Sunglasses can reduce the incidence of surface eye cancers and possibly the deeper ones.