Drawing the shades

April 12, 1994|By James Raia | James Raia,New York Times Special Features

Sunglasses fascinate society, often for all the wrong reasons. We long to purchase the latest trends and styles. We wear sunglasses indoors and at night. We perch them on top of our heads and hang them around our necks as much as we use them for the reason they were invented.

The American Optometric Association (AOA) calculates that nearly $2 billion is spent each year on an estimated 105 million pairs of sunglasses.

But the perceived mystique and glamour of sunglasses, and the "coolness" associated with wearing them, should never be overshadowed by a more important issue: Wearing quality sunglasses can protect your eyes against exposure to the harmful ultraviolet (UV) radiation of the sun.

"There's a lot of hype in the sunglass market," says Dr. Donald G. Pitts, professor of environmental vision and anatomy at the University of Houston College of Optometry. "The fancy words mean nothing, except the sunglasses usually cost more."

Prescription and non-prescription sunglasses are available in a wide variety of styles, prices and needs.

Besides such qualities as durability and frame construction, consumers should also be concerned with the percentage of ultraviolet radiation protection, light blockage, polarization, optics and proper color vision characteristics.

Without these, consider the consequences: Exposure to ultraviolet radiation, which is particularly abundant in natural sunlight reflected off snow or sand and at high altitudes, can cause keratoconjunctivitis, a temporary inflammation of the eyelid lining or the cornea. Snow skiers call the condition snow blindness.

More devastating, UV radiation can permanently damage the retina, the delicate vision mechanism inside the eye.

UV radiation is also a leading contributor to cataracts, the clouding of the eye lens that obstructs the passage of light.

"I don't think people have to be paranoid and protect their eyes indoors and every time they step outside," says Dr. Anthony Cullen, former director of the School of Optometry at the University of Waterloo in Canada.

"But if it's bright out, if there's either reflected or direct sunlight, they should wear protective sunglasses. It's best to err on the side of caution."

Concern over cataracts

Dr. Cullen's concern is well-founded and reiterated in stronger terms by many of his optical contemporaries.

"Cataracts are a public health concern of major proportions," says Dr. Richard W. Young, professor emeritus of anatomy at UCLA and author of "Age Related Cataract" (OUP, 1990).

"In a normal life span, cataract surgery is the most likely operation you'll have," he says. "And anyone who is not preventing UV rays from striking their eyes simply doesn't know what's going on.

As one of the three components of solar energy, invisible ultraviolet radiation has three levels, defined as UV-A, UV-B and UV-C.

The range of ultraviolet light is determined by nanometers, the international wavelength measurement. One nanometer equals one-billionth of a meter.

Ultraviolet-C is solar energy measured below 286 nanometers. Ultraviolet-B is defined as 286 to 320 nanometers and UV-A is 320 to 400 nanometers.

Although it may change as the ozone layer further erodes, UV-C radiation is believed to be effectively absorbed by the ozone, the Earth's upper oxygen atmosphere.

Ultraviolet-B is the solar energy that causes sunburn. Although the potential dangers of UV-A are not as well documented, most eye experts believe sunglasses should protect against UV-A and UV-B as contributors to short-term and long-term eye damage.

But even sunglass manufacturers whose products offer appropriate UV protection are misleading consumers, says Charles Bernheiser, product development director of Gargoyles, which is credited as the first manufacturer of wraparound sunglasses.

Information or hype?

"It seems to me that a lot of companies are picking up on new UV information simply for hype," Mr. Bernheiser says.

In addition to the percentage of UV protection, consumers should also consider optical quality, frame construction, proper color vision characteristics and other lens options such as polarization and mirror finish.

Polarization is a lens process that effectively filters out reflected glare off snow, water, sand, pavements and windshields.

Non-polarized sunglasses reduce total glare to a comfortable level but don't eliminate reflected glare.

While glare is not believed to be permanently harmful to the eyes, it can cause reduced and unsafe vision, squinting and watering eyes.

Mirrored sunglasses have the same properties as a two-way mirror. They provide maximum infrared light protection and are designed to wear in glare from snow or water.

To help consumers select appropriate sunglasses, the U.S. Food and Drug Administration announced a voluntary labeling system 1989.

Labeled for protection

The program, developed by the FDA and the Sunglass Association of America, suggests manufacturers' labels include BTC UV protection information and recommended uses.

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