What to Look For in a Pair of Sunglasses
As you slather on sunscreen to protect your skin this summer, don't forget sunglasses to protect your eyes. The same harmful rays that damage skin can also increase your risk of developing eye problems, such as cataracts--a clouding of the eye's lens that develops over years.
In the short-term, people who spend long hours on the beach or in the snow without adequate eye protection can develop photokeratitis, reversible sunburn of the cornea. This painful condition can result in temporary loss of vision. When sunlight reflects off of snow, sand and water, it further increases exposure to ultraviolet (UV) radiation. These invisible high-energy rays lie just beyond the violet end of the visible light spectrum.
Everyone is at risk for eye damage from the sun year-round. The risk is greatest from about 10 a.m. to 4 p.m. Fishermen, farmers, beach-goers, and others who spend time in the sun for extended periods are at highest risk.
UV radiation in sunlight is commonly divided into UVA and UVB, and your sunglasses should block both forms. Don't assume that you get more UV protection with pricier sunglasses or glasses with a darker tint. Look for a label that specifically states that the glasses offer 99 percent to 100 percent UV protection. You could also ask an eye-care professional to test your sunglasses if you're not sure of their level of UV protection.
Sunglasses should be dark enough to reduce glare, but not dark enough to distort colors and affect the recognition of traffic signals. Tint is mainly a matter of personal preference. For best color perception, Prevent Blindness America, a volunteer eye health and safety organization dedicated to fighting blindness and saving sight, recommends lenses that are neutral gray, amber, brown or green. People who wear contact lenses that offer UV protection should still wear sunglasses.
Children also should wear sunglasses. They shouldn't be toy sunglasses, but real sunglasses that indicate the UV-protection level just as with adults. Polycarbonate lenses are generally recommended for children because they are the most shatter-resistant.
Sheryl Berman, M.D., a medical officer in the FDA's Division of Ophthalmic and Ear, Nose, and Throat Devices, says that wearing sunglasses reduces the risk of eye damage due to sun exposure, but doesn't completely eliminate it.
"Even when we talk about 100 percent UV protection, light still enters from the sides of sunglasses and can be reflected into the eye," she says. Some people choose sunglasses that wrap all the way around the temples. A hat with a three-inch brim can help block sunlight that comes in from overhead.
The FDA's Center for Devices and Radiological Health regulates nonprescription sunglasses as over-the-counter medical devices. Sunglasses are normally exempt from the FDA's premarket notification procedures. But sunglasses manufacturers who claim their products are of substantial importance in preventing health problems would be required to submit proof to the FDA. The only medical claim manufacturers are allowed to make on sunglasses is that they may reduce eye strain or eye fatigue due to glare.
Even though sunglasses are exempt from premarket notification, they remain subject to several regulations. Sunglasses regulated by the FDA must comply with impact-resistant requirements, for example. This doesn't mean that the glasses are shatterproof, but that they can withstand moderate impact. Sunglasses are not intended to function as protective eyewear in high-impact sports.
Manufacturers of sunglasses also must follow the FDA's labeling regulations. The FDA has issued warning letters to manufacturers about unsubstantiated performance claims, such as those relating to UV-absorbing sunglasses.
For more information about how the FDA regulates sunglasses, you can access a sunglasses guidance document: Guidance Document For Nonprescription Sunglasses.
UVA and UVB
- UVA: UVA is ultraviolet radiation with wavelengths from 320-400 nanometers. It passes through the Earth's ozone layer and can cause early aging of the skin.
- UVB: UVB is ultraviolet radiation with wavelengths of 280-320 nanometers. The ozone layer absorbs most of the sun's UVB, but even a small amount can do substantial damage. UVB causes skin cancer and may contribute to cataracts.
by Michelle Meadows
FDA Consumer magazine