BOULDER, Colo. _ Revos are not just a fashion statement anymore.
With a depleting ozone, aging population and changing lifestyles that are leading more people outdoors, wearing sunglasses means more than being hip. It means healthy eyes.
Research linking ultraviolet radiation to vision-impairing eye diseases continues to grow, and experts want people to start taking note _ particularly athletes and people who live in higher elevations.
``Epidemiological studies have demonstrated that people who live in Sunbelt areas, high-altitude areas or areas that have a lot of cloudless days are at a higher risk,'' says Boulder ophthalmologist Gerald Carp.
The latter two factors define Colorado, with its mile-high city and 300-plus sunny days a year.
``If you're living at higher altitudes, there's less space between you and the sun,'' says David Johnson, M.D., an assistant professor of ophthalmology at the University of Colorado Health Sciences Center in Denver. Scant cloud cover and dry climate give Coloradans fewer natural filters to block some of the sun's damaging rays, he explains.
Factor in an active lifestyle and mountain sports, and many people should be reaching for their sunglasses.
``We're all very familiar with the effect of UV rays on the skin, but now we feel strongly that we should pay more attention to the eyes,'' says Alan Berman, a doctor of optometry and co-director of the Institute for Sports Vision in Ridgefield, Conn.
``Athletes,'' says University of Colorado research associate Betsy Weatherhead, ``are at particular risk for damaging their eyes from natural UV, because athletes are usually very focused on something, like a volleyball.'' Weatherhead, whose research focus is on measuring UV light, points out that people walking down the street or standing on the corner talking tend to tilt their heads away from the sun's rays. ``They never let the sun enter directly into their eyes. Athletes will direct their eyes wherever their sport forces them to be, regardless of if the sun is directly behind that point,'' Weatherhead says.
Contrary to some previous reports, Weatherhead's most recent research shows UV light has been increasing a few percentage points each year, hiking the danger to athletes even further.
``We've worked a lot with athletes,'' says Berman, who has served as a sports vision consultant for professional golf and tennis tours and U.S. Olympic athletes among others. ``I've seen the effects on people during the 15 years that I've practiced.''
Those effects range from cataracts to ``fleshy growths'' to retinal degeneration. But one effect that might ring familiar to sports enthusiasts is ``snowblindness,'' a form of photokeratitis, or sunburn to the eye. Those who have had it, know it, the doctors agree.
``The surface cells for the cornea die and slough off and leave nerves exposed,'' says Johnson.
``It's extremely painful,'' says Morris Tilden, M.D., a Longmont, Colo., ophthalmologist, who says he sees a number of skiers each year who damaged their eyes when they forgot their sunglasses. ``Mostly flatlanders.''
Skiers don't even realize something is wrong until the damage is done, Tilden says. ``It really doesn't start kicking in until about seven hours later. They come into the emergency room about 2 a.m.,'' he says. He treats the malady with pain pills, antibiotic ointment to prevent infection and steroid drops to reduce inflammation.
``Generally, it clears up in about 24 hours,'' says Berman, noting that eyes become hypersensitive to the sun and feel irritated and gritty. Those who experience snowblindness or another form of photokeratitis once are likely to experience it more quickly the next time they allow overexposure, Berman says.
Snowblindness earns its name because of the reflection factor, when UV rays bounce off of a surface and into the eyes.
``Even people in urban areas can get extra UV from light bouncing off sides of buildings, particularly those with glass sides,'' says Weatherhead.
``And snow happens to be immensely reflective of ultraviolet light,'' Carp says. It beats all other surfaces in the reflection contest, with grass weighing in at 1 percent, sand at 10 percent, water at 20 percent and snow at 80 percent.
``So,'' Carps says, ``if you're at high altitude on a cloudless day in a snowfield,'' sunglasses definitely would be in order.
Research continues to build on the sun's negative effects on the eyes, with macular degeneration _ a chief cause of blindness in the nation's senior citizens _ garnering renewed attention.
``As the nation ages, we are going to see research take off in the area,'' says Johnson, who specializes in the disease.
Carp emphasizes that macular degeneration has not been undeniably linked to ultraviolet-ray exposure, as photokeratitis and some forms of cataracts have, but studies strongly indicate a connection. Both he and Johnson attribute the increased incidence in the blinding and often irreversible disease to longer lifespans.
And, unlike photokeratitis, which can be prevented with good eye protection, other eye diseases related to UV light have additional causes. Macular degeneration, for instance, is related to aging, heredity, smoking, cardiovascular disease and poor diet, Carp says.
``The disease is a breakdown of the components in the central area of the retina called the macula,'' says Carp. ``It is the area responsible for the finest vision.''
Degeneration of the macula affects about 90 percent of the disease's victims, and doctors cannot stop the resulting blindness, Johnson says. But much research is under way, focusing on medical treatment, radiation therapy and surgery, Johnson says. ``And right now there are a lot of trials going on with vitamin therapy,'' he says. Some believe the antioxidants (A, C and E) could help slow or halt the process.
``There's a complication of macular degeneration where abnormal blood vessels can grow under the macula,'' Johnson says. The Health Sciences Center hopes to take part soon in some laser studies used to treat that condition, which strikes about 10 percent of macular degeneration patients, he says. ``You're basically using the laser light to cauterize those vessels. That can be very helpful, but often the problem recurs.''
Retinal damage from UV light is much less common than other problems, such as cataracts, cancerous growths and pterygia. The natural UV protection of the eye is in the cornea (the outside surface where pterygia occur) and the lens (behind the pupil where cataracts form). The two absorb all UV-B and most UV-A light, the former being the shorter and more damage-causing rays, according to the Washington Association of Optometric Physicians. So only between 0 and 3 percent of the UV rays reach the retina, says Tilden. But the amount allowed in can rise as the damage to the eye increases.
All doctors emphasize the latter point, noting that eye damage is cumulative, with extreme cases showing up frequently in people who live at high altitudes or work in the sun all day.
Pterygia, for instance, frequently shows up in people who live near the equator and in migrant workers, Johnson says. ``A pterygium is a little sort of fleshy growth that can grow over the cornea and distort vision,'' he says. The growths can be removed with surgery, but often the resulting scarring distorts vision, says Carp. And Johnson adds they often grow back.
Cataracts are actually a natural clouding of the eye in response to the UV light which, in some people, goes too far, distorting and eventually occluding vision. This natural course explains why children's eyes are more susceptible to the sun's dangerous rays. ``There's a normal yellowing of the lens in adults,'' says Carp, that increasingly blocks UV light. While children haven't yet developed that and thus do get more UV rays into the eye, their eyes are ``more capable of fending off the insults,'' he said.
In cataract patients, lens implants are used to replace the clouded lens. The procedure used to dramatically reduce the patient's natural level of UV protection, but the implants now are UV protected. Those whose surgery was not recent should pay close attention to UV exposure.
Cancerous growths around the eye are also found more commonly in people with extended UV exposure.
Weatherhead emphasizes that Coloradans face greater danger from ultraviolet radiation. ``Some people can be lulled into thinking: `It's a cool day; UV isn't an issue,''' Weatherhead says. But the cool climate that slightly cloudy days and high elevation create can be very dangerous, she says. Cloud coverage does not equate to UV protection unless it is really significant coverage.
Scant coverage does more than create a sense of protection while letting rays through; those clouds can actually reflect the rays and intensify the exposure, she says. ``They act like a mirror. Emergency rooms see their worst sunburns on those days,'' Weatherhead says.
And while Weatherhead says scientists are expecting to see ozone depletion reverse within ``a couple of years,'' she would not be putting her sunglasses away anytime soon.
``I think the biggest threat is that we have difficulty predicting,'' she says, noting that scientists did not predict the ozone holes there are now. There's a lot we don't understand. We can't have a whole lot of confidence at this time.''
Doing everything possible to protect one's eyes is crucial, including understanding high-risk factors, wearing quality protective gear and getting regular eye exams, the experts agree.
``There are a variety of problems that the eyes experience from UV radiation,'' Weatherhead says. ``It's very important to take care of your eyes.''
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(c) 1997, Daily Camera (Boulder, Colo.).
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