Embarrassing, but true—when we go to the beach, we worry about shark attacks or sting rays. In fact, true threats are often much less dramatic but all the more real: A day on the water should have us more concerned with sun damage.
Eye disorders and cancers related to excessive sunlight exposure occur most frequently among older people and in those with fair skin and light-colored (blue or green) eyes. However, these conditions can, and do, occur in all kinds of people.
Ultraviolet (UV) radiation is simply energy of a particular wavelength that spreads out (radiates) from its source—in this case, the sun—the way the spokes of a wheel radiate from the hub. The sun’s electromagnetic energy consists of UVA, UVB, and UVC rays. Short-wavelength UVC rays are blocked by the ozone layer that envelops the Earth.
Medium-wavelength UVB rays are those that cause sunburn and premature skin aging. Long-wavelength UVA rays are those that tan the skin. They’re also emitted by tanning beds and sunlamps.
The eyelids limit the amount of light that can enter the eye, but their tissues are thin, delicate, and vulnerable to the chronic effects of exposure to UV radiation. The eye’s surface, the cornea, admits light and screens out nearly all of the UVB radiation in sunlight, protecting the lens and retina. The lens filters UVA radiation and absorbs light in order to focus on images.
Short-term Effects of UV Exposure
Exposure to the UV radiation in sunlight may cause eye discomfort, but this minor irritation usually resolves quickly.
Photokeratitis is a painful corneal burn caused by short-term exposure to UVB rays from any highly reflective surface, such as concrete, water, sand, or snow. Tanning beds may also cause photokeratitis, and goggles offer little protection. Photokeratitis lasts 1 or 2 days and may cause temporary vision loss. Long-term damage to the cornea and conjunctiva may be linked to the condition.
Long-term Effects of UV Exposure
Exposure to UV radiation has been associated with a number of disorders, some of which pose a threat to vision:
Cataracts is a clouding of the lens, a transparent, layered structure that lies behind the iris. A cataract obscures vision by making objects look hazy. Scientists have theorized that decades of exposure to UVA radiation may cause the lens to discolor and harden into a cataract. Newer studies have not confirmed an association between sunlight exposure and cataracts, though, and research is under way to investigate the link.
Age-related Macular Degeneration (AMD:
AMD destroys the macula, a cluster of light-sensitive cells in the retina that gives you crisp central vision and allows you to perceive fine detail. New research suggests that long-term exposure to high-energy visible (HEV) radiation from the sun, sometimes called "blue light," may damage the macula. In addition, some studies have found an association between exposure to UVA radiation and the development of AMD. Further research is needed before exposure to solar radiation can be considered a risk factor for AMD.
Pterygium and Pinguecula:
A pterygium (pronounced tuh-RIJ-ee-um, with a silent "p") is a thin, wedge-shaped growth of fibrous tissue extending from the corner of the eye to the cornea. The word pterygium comes from a Greek word meaning "little feather," in reference to its shape. A pterygium (plural pterygia) is not cancerous and grows slowly, but it may spread over the cornea enough to impede vision. If so, surgical removal may be required. Some patients have pterygia removed for cosmetic reasons. A pinguecula is a yellowish patch or lump on the conjunctiva, the transparent membrane that covers the white part of the eye (see How the Eye Works). More nodular in shape than a pterygium, a pinguecula is a noncancerous accumulation of protein and fat deposits. Like a pterygium, it grows slowly; however, it does not invade the cornea.
Several kinds of eye and eyelid cancers are linked to excessive sunlight exposure. Basal cell carcinoma is by far the most common, accounting for more than 90% of all eyelid cancers. Only about 5% of eyelid cancers are squamous cell carcinomas. Melanoma can occur on the skin near the eye or in the eye itself (ocular melanoma).
Protection from UV Radiation
UV protection can be incorporated into eyeglasses, sunglasses, contact lenses, and even intraocular lens implants placed in the eye during cataract surgery. We can shield ourselves from sun damage in other ways, too.
You need not sport a designer label or shell out a week’s pay to buy a good pair of sunglasses. Look for those that block 99% or more of UVA and UVB radiation. The lenses should match in color and be free of flaws and distortions. Choose a wraparound style for the best UV protection, and make sure they allow good color recognition so that you can respond safely to traffic signals. Polarized lenses will reduce glare when you’re in the snow, on the water, or driving.
Wear UV Blocking Contact Lenses:
Contact lenses that incorporate UV-blocking optical materials offer added protection because they can filter out UV rays that stray past hats and sunglasses. FDA Class II lenses are intended for general use, and class I lenses are suitable for those who plan to be in the snow, on the beach, or in any other highly reflective environment.
Wear a Hat:
Broad-brimmed hats aren’t as high-tech as UV-blocking contact lenses, but they’re very effective in shading your eyes, as well as your skin, from solar radiation. In fact, a hat with a wide brim (3 in. or more) can block about half of the UV radiation from the sun and reduce the amount of sunlight that shines in around the edges of your sunglasses.
Minimize Sun Exposure:
Another simple but effective way to reduce your risk from UV exposure is to stay out of the sun, particularly between 10 a.m. and 2 p.m., when sunlight is most direct.
When applying sunscreen, don’t forget your face and eyelids. Apply sunscreen with a sun protection factor (SPF) of 15 or higher about a half hour before you engage in outdoor activities, and reapply it every couple of hours if you’re sweating or swimming.
Look Out for Children:
Nearly half the time we spend outside during our lives happens while we’re kids. In addition, children’s eyes aren’t as good at screening out UV rays as adult eyes are. Parents and guardians should purchase sunglasses, hats, and sunscreen for children and make sure they wear them. In choosing sunglasses, look for high-impact lenses that won’t break easily, and secure the glasses with a Velcro strap to make sure they don’t get lost.
Once you and any children in your care are suited up in hats and sunglasses and have been slathered with sunscreen, enjoy your time outdoors.