Be kind to your eyes: Wear hat, sunglasses Study finds sunlight adds to cataract risk

August 26, 1998|By Diana K. Sugg | Diana K. Sugg,SUN STAFF

Finding that exposure to sunlight increases the risk of cataracts, researchers recommended yesterday that everyone use sunglasses, hats and other steps year-round to cut down on harmful rays.

Scientists had known from earlier studies that people who work outdoors, such as Maryland watermen, developed more cataracts than people with less sunlight exposure.

But until now, researchers didn't know whether ultraviolet-B rays posed a cataract risk to the general population.

Sheila West, a Hopkins professor who was the study's author, said she expected to find deterioration after a high level of exposure.

Instead, she was surprised to discover that damage from ultraviolet-B rays is cumulative over a person's lifetime, potentially leading to cataracts, a major cause of blindness and disability.

"Every time you go out into the sun, your eyes can take a hit from UV-B rays," said West, a professor of ophthalmology at the Johns Hopkins Wilmer Eye Institute. The study appears in today's issue of the Journal of the American Medical Association.

But wearing glasses may stop only a small percentage of cataracts. Researchers say other factors, such as age, diabetes and certain medications, also increase risk. More than half of all Americans over age 65 have some evidence of cataract.

"You could stay inside all day long, and you may still get a cataract," said Dr. Allan Rutzen, co-director of the external eye disease service at the University of Maryland Medical Center. But he added that the new findings had been suspected for some time and the Hopkins study was the best of its kind to date.

West was able to calculate that for every 1 percent increase in "Maryland sun year" that a person gets, there's a 10 percent increased risk of cortical cataract, one of the most common types. The study also found that this level of risk applies equally to whites and African-Americans, and to women and men.

"There is no safe dose, in essence," West said.

But simple steps can protect the eyes. Hats with a brim can cut down UV-B rays by as much as a third, West said. Any pair of cheap plastic sunglasses will also do.

The deluxe, $80 versions don't offer any more UV-B protection than inexpensive ones.

West's group sampled about 30 pairs of sunglasses, from drugstore varieties to the ones that sit inside locked glass cases. The winner: a free pair she got at an Orioles game.

"From a UV-B standpoint, if we can get people to wear anything, they all work," West said.

Plastic is the key; regular plastic glasses, not just the tinted ones, provide protection from UV rays. Because most contact lenses are made of artificial compounds, not plastic, they don't offer any protection, physicians said.

Glasses made of glass, even if they are shaded, will also let in some UV-B rays.

Ultraviolet radiation is one small part of the spectrum of radiation that makes up sunlight. The visible sunlight is the light shaded sunglasses help reduce.

UV-B rays, on the other hand, are invisible. They can penetrate cloud cover and are considered the most biologically active and damaging rays.

Sunglass makers, whose market has doubled over the past decade to $2.6 billion in 1997, are pleased. According to Richard Enholm of the Sunglass Association of America, almost all sunglasses, regardless of price, offer more than 97 percent protection of UV-B and a related damaging ray, UV-A.

With 2,520 adults, ages 64 to 84, in Salisbury, Wicomico County, as the study group, the Hopkins research focused on cortical cataracts, which affect the front of the lens.

Like a camera, the lens focuses light on the retina of the eye; it's important that it be clear so light can pass through undistorted. As people grow older, the lens often clouds over. This area, the cataract, may gradually grow and block vision.

Researchers believe that when UV-B rays hit the lens, it absorbs most of the light, protecting other eye structures. But the UV-B rays reconfigure proteins in the lens, West said, clumping them together and scattering light away from the retina, making images appear fuzzy, as if a shower curtain were over the person's eyes.

In most cases, surgery can correct cataracts. According to West, in 1991, Medicare's bill for cataract surgeries was about $3.4 billion, or 12 percent of the total Medicare budget.

At the National Eye Institute, officials endorsed the idea of wearing glasses and hats.

"I don't think one should assume that we're going to take care of the cataract problem with these measures, but anything one can do with a problem as large as cataract, is useful," said Dr. Robert Sperduto, chief of the epidemiology branch.

Whether children should follow the recommendations may be controversial.

While acknowledging the difficulty of keeping hats and glasses on kids, West said that there was no reason to think children's lenses were biologically less susceptible to damage.

Dr. Andrew Iwach, an assistant professor at the University of California-San Francisco and a spokesman for the American Academy of Ophthalmology, said a hat is a good bet.

"Harmful radiation takes a toll on us," Iwach said. "But this is a long-term issue. If you forget your hat one day, it's OK to go to the baseball game."

Pub Date: 8/26/98

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