Shielding Your Eyes from the Sun

by Food and Drug Administration (FDA)

Headed for the ski slopes or beach? These pleasures can pose dangers to your eyes unless you take precautions against the sun's harmful rays.

Ultraviolet radiation is invisible and cannot be felt, yet long-term exposure to it may be associated with development of cataracts. Short-term exposure to very intense ultraviolet light — such as you get on a ski slope — can produce photokeratitis, also called actinic keratopathy or snow blindness. There is even some evidence ultraviolet radiation may damage the eye's retina.

By spring of 1990, a new voluntary labeling program developed by the Sunglass Association of America in cooperation with the Food and Drug Administration is expected to be in place to tell consumers how much UV protection they can expect from nonprescription sunglasses. (Prescription sunglasses already meet standards of protection against UV radiation and are not included in this labeling program.)

The voluntary labeling program calls for manufacturers to attach a tag to sunglasses that specifies the level of protection from the two types of ultraviolet rays: the longer wavelength ultraviolet A (UVA) radiation and the shorter wavelength ultraviolet B (UVB) rays. The standards were developed in 1986 by the American National Standards Institute in New York City through consultation with eye-care professionals and educators, research scientists, industry, and military and other government agencies. The labeling standards are the only recognized statement on the properties and performance of sunglasses.

The different categories describe minimum levels of protection and are designed to help consumers pick the best glasses for the types of activities they plan:

Cosmetic: For non-harsh sunlight and around-town uses such as shopping. These will block at least 70 percent of UVB, 20 percent of UVA, and less than 60 percent of visible light.

General Purpose: For most outdoor activities such as boating, flying, hiking, picnicking, and beach outings. They also can be used for snow settings. They will block at least 95 percent of UVB, at least 60 percent of UVA, and from 60 to 92 percent of visible light.

Special Purpose: For very bright environments such as tropical beaches and ski slopes and for activities like mountain climbing. They will block at least 99 percent of UVB and 60 percent of UVA, in addition to from 20 to 97 percent of visible light.

The amount of visible light — glare — blocked by sunglasses depends on the darkness of the lenses. The darker shades of special-purpose sunglasses are intended for a high level of brightness, while the lighter shades can be used for less bright situations like skiing on a cloudy day.

In addition, within the categories, look for the actual percentage of the sun's UV radiation that each particular model of glasses claims to block. The greater the blockage, the lower the risk of UV damage to the eye.

Thomas Loomis, technical director of the Sunglass Association of America, offers this advice when buying nonprescription sunglasses:

First, decide on the purpose, color and fashion you want. Once you've made a selection, hold the sunglasses up at arm's length and look through them at an object with a straight border, such as window or door frame. Move the glasses slowly across the line. If it seems to wiggle, sway or curve, the lenses contain an optical defect and should be replaced with another pair.

Since 8 percent of males and 3 percent of females have a vision color defect, be sure the glasses don't distort the colors of a traffic signal. Pay for the glasses, says Loomis, walk outside the store and conduct your own test. If they distort the colors, exchange them for another pair.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.