And you may not notice the damage that's being done, he adds, because long-term damage can take years to show up. Severe short-term effects of sun damage can produce irritation, tearing up, sensitivity to bright lights, and a burning sensation. "A common complaint is that it feels like you have sand in your eyes," he says. These usually take a few hours to appear, "but if you get a good burn, you'll suffer for a couple of days." Chronically underprotected eyes can develop cataracts or a disease called pterygium, a condition that can cause vision problems or even blindness. Pterygium is common in middle-aged and older adults, he says; in the South, where people are closer to the equator and spend more time outdoors, it affects up to 10 percent of the population. And, he notes, UV radiation is its only known cause.
Before the long Fourth of July weekend hits, spend some time shopping for good-quality sunglasses, paying close attention to a few details:
• "Polarized" does not equal "UV protection." "The fact that a pair of sunglasses could be polarizing has nothing to do with UV absorption," he says; polarized sunglasses simply reduce glare, and unless they're treated with a UV-protective coating, don't protect against UV rays. Dr. Bergmanson says to look specifically for sunglasses that advertise themselves as having UV protection and particularly those advertised as meeting certain criteria set by the American National Standards Institute (ANSI). At the very minimum, ANSI requires that sunglasses block 95 percent of UVB rays and 70 percent of UVA rays, but you can get better protection from "class 1" ANSI-rated glasses, which block 99 percent of UVB rays and 95 percent of UVA rays. This rating should be advertised on a product label somewhere, but if you're in doubt, ask your optometrist, says Dr. Bergmanson. Optometrists have equipment that can detect the UV protection level of sunglasses and corrective eyeglasses that have been treated with a UV coating. If there's no product label, assume that there's no UV protection. While you're shopping, look for wraparound shades, he says, so you block UV rays that can enter from the sides of your glasses.
• Hats are good for your skin, but not for your eyes. Hats protect your ears, your neck, and your face from harmful rays, but, says Dr. Bergmanson, "they're of limited value when it comes to your eyes." Just 50 percent of UV rays come from direct sun-to-eye contact. The rest of them are from ambient, reflected radiation that bounces off surfaces. "We first discovered the association between sunlight and corneal burn in Sweden," he says, "because the number one source of reflected UV radiation is off snow." The second highest source, he adds, is the ocean. So keep your hat on, but make sure your eyes are protected as well. If you're worried about sand scratching an expensive pair of shades, ask your salesman to add a scratch-resistant coating.
• Try contacts. "Honestly, I think nothing beats a contact lens when it comes to protecting the eye from UV damage," Dr. Bergmanson says. Most of the major contact lens manufacturers now add UV filters to the lenses, and because they sit right on top of your eye, they provide the most complete protection against UV rays, even when you don't feel like putting your sunglasses on. Of course, if you don't need corrective lenses, this isn't a logical choice. Eyeglass wearers who aren't eager to switch to contacts can also ask their optometrists to apply UV coatings to their lenses; coatings approved by the American Optometric Association block 99 percent of UVB and UVA rays. "Remember," says Dr. Bergmanson, "it's not the occasional sunburn that really counts. It's the lifetime dose that does the most damage."