A SHATTERING LOOK AT EYEGLASS SAFETY.

Byline: Peter Modica Medical Tribune News Service

Many eyeglass lenses that conform to current safety standards still pose a potential health hazard because they are not shatter resistant, according to a new study.

While eye-safety standards set by the U.S. American National Standards Institute have helped prevent thousands of eye injuries by keeping extremely fragile lenses off the market, these standards are still too low, researchers reported in a recent issue of the Journal of the American Medical Association.

Current regulations require that lenses should resist breaking when hit with a steel ball traveling at 11.2 miles per hour, noted the researchers led by Dr. Paul F. Vinger of Tufts Medical School in Medford, Mass.

But after testing four types of available lens materials, they found that eyeglass lenses made from glass, allyl resin plastic or high-index plastic did not resist breaking when struck with objects such as golf balls or baseballs traveling at speeds lower than a person might encounter in everyday life. Golf balls, for example, shattered certain lenses at 25 miles per hour - slower than many golf balls travel.

The researchers tested daily-wear glasses, sunglasses and industrial safety glasses.

Only one type of lens material - polycarbonate plastic - showed potential in helping reduce eye injuries by resisting breakage, the researchers said.

Proper eyewear can prevent an estimated 90 percent of sports and work-related eye injuries, they noted.

``People need to realize that they have the option to put something in front of their eyes that is harder to break and more protective of their eyes,'' Vinger said.

Shattered eyeglasses pose a dangerous threat since the glass shards can damage the eyes, Vinger said.

``Most people think these lenses are shatterproof because they pass safety standards,'' Vinger said. But the standards are set too low and should be re-evaluated, he said.

Based on the new findings, people who play sports or who work around flying materials should consider using eyewear with polycarbonate lenses, said Dr. John Jeffers, director of emergency medicine at the Will's Eye Hospital in Philadelphia.

``In most instances, polycarbonate lenses are certainly the way to go,'' Jeffers said.

The majority of sports goggles, including racketball goggles and hockey face guards, are made of polycarbonate plastic, he pointed out.

Polycarbonate lenses tend to cost $20 to $75 more than the regular plastic or glass lenses, and it is more difficult to make dark sunglasses or bifocals from this plastic, Vinger said.

Still, as many as 98 percent of prescription glasses could be made with this more protective material, he said.

Such protection could mean the difference between saving a person's eyesight or losing it, Jeffers said. ``The question is: Do you spend a little more on polycarbonate lenses or on health care after the fact?'' he said.

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Photo: Even some plastic lenses can shatter if hit by an object at high speed, say researchers who recommend using stronger plastics in eyeglasses.