Watching Out For A Shady Deal

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ther you're headed for the beach or the lake, or whether you just plan to hang out in the backyard this summer, you probably already know how to protect your skin against the sun's harmful rays. Just slip on a shirt, slap on a hat and slop on plenty of sunscreen, preferably with an SPF rating of at least 30. But are you doing everything you can to safeguard your eyes? Don't be so sure the answer is yes, even if you sport the latest in designer sunglasses.

Many shades on the market don't fully block the two main types of ultraviolet radiation (A and B) that have been linked to everything from wrinkles to sunburn to skin cancer. Ophthalmologists are increasingly convinced that prolonged exposure can lead to a host of vision problems as well.

Sometimes the trouble shows up right away. Water skiers, or snow skiers for that matter, can develop a type of temporary blindness, called photokeratitis, that occurs when reflected sunlight actually burns the cornea, the clear covering over the eye. Other conditions may be triggered after years of exposure. Studies have linked UV radiation to an increased risk of cataracts, in which the lenses of the eyes become cloudy, as well as to macular degeneration, in which the cells in the central part of the retina slowly die.

The right pair of sunglasses doesn't have to burn through your bank account. Whether you're eyeing a $175 pair of Persols or a $20 bargain from the drugstore, make sure there's an official decal indicating that the lenses absorb 99% to 100% of the UVA and UVB rays. What you shouldn't accept, however, is any nonspecific wording such as "UV block" or "maximal UV protection." Specific numbers should always be attached.

Without the right decal, deeper tints can actually make things much worse. It's normal for our eyes to widen and let in more light when we wear dark glasses. Unless the lenses are already designed to absorb ultraviolet light, the risk of damaging the eyes only grows.

For a little extra margin of safety, choose lenses that are "polarized." This cuts down on glare by deflecting the sunlight that bounces off such smooth surfaces as sand, water and pavement.

The style of the frames can be as important as the lenses, and the trick here is to protect your eyes not only from direct light but also from the light that strikes at different angles, whether from above or the sides. Wraparound frames that fit snugly against your face are most effective at closing off these open spaces. Even those large Jackie O frames that have come back into style are a good choice because they cover all of the eye socket and surrounding areas.

Don't forget the kids. Chances are they are outdoors more than you. Whatever you do, don't toss your sunglasses once summer is over. Ultraviolet radiation doesn't disappear on cloudy days or in winter. Preserving your vision is a year-round job.

Dr. Ian is a medical correspondent for NBC's Today show. E-mail: ianmedical@aol.com