The next time your sunglasses slide down your sweaty nose right in the middle of that heated tennis match, you might wonder: Why don't they make sunglass contact lenses?

	Nike Maxsight contact lenses come in a grey-green tint and an amber tint, shown above, to enhance different parts of the light spectrum for different activities.

Well, now they have.

The Nike Maxsight sport-tinted soft contact lenses, hitting the market this month, are designed with special technology that allow athletes and outdoor enthusiasts to see sports action with greater clarity.

But they could be just as valuable to others who spend a lot of time outdoors, such as construction and road workers.

"In terms of making lenses a sunglass, this is a unique product,'' said Amy Nau, director of optometry at the UPMC Eye Center.

"I think it's good,'' said Nau, who struggles herself with sunglasses when playing outdoor tennis. "It will be very interesting to see if people like them.''

Produced in a joint venture between Nike Inc. and Bausch & Lomb, the lenses were cleared by the Food and Drug Administration in May. They have been tested by a few athletes, including Baltimore Orioles second baseman, Brian Roberts.

The UPMC Eye Center plans to make them available to University of Pittsburgh athletes when the lenses arrive.

The lenses come in two tints: grey-green and amber.

Bausch & Lomb describes its patented Light Architecture and the importance of the colors in what sounds like marketing mumbo jumbo. But Nau said there's a whole science in color vision and color theory. "That is actually valid,'' she said.

The grey-green lenses are designed to enhance the green and red portions of the visual spectrum of natural sunlight to improve detail and contour recognition. This is ideal for sports played in bright sunlight such as golf, football, running and rugby.

The amber assists athletes playing fast-moving ball sports played in variable light such as soccer, tennis, baseball and softball. The tint selectively filters wavelengths in the blue-green portion of the visible spectrum, making the ball pop out of the background.

Other products are adopting that same technology. Nike has introduced golf sunglasses with the same amber tint as used in the soft lenses.

Polarized lenses, which reduce glare, have been out for a while, as have wraparound sunglasses that don't restrict peripheral vision.

But it's only been recently that wraparound prescription sunglasses have been introduced. Specialists had a difficult time crafting lenses that didn't get distorted by the design, Nau said.

Most tinted contacts on the market are sold only for cosmetic purposes to change the appearance of the color of a person's iris. They don't block out certain wavelengths of light. The cosmetic lenses also cover a much smaller surface area of the lens.

While the Nike Maxsight lenses filter most of the potentially harmful ultraviolet light, they don't provide full UV protection of the eye and surrounding ocular tissue that regular sunglasses do.

Nike Maxsight lenses are for those who are near-sighted or far-sighted, but consumers can also get noncorrective lenses. All must be fitted by an eye professional, primarily optometrists.

The lenses sell in boxes of six at a cost of $60, which is about $20 more per pack than regular soft, disposable lenses, said Tor Constantino, spokesman for Bausch & Lomb.

Each pair should be replaced monthly, even if they're used just for outside activities, said Nau, who noted they would be too dark to wear all day to the office.

"Most people's contact lens cases are extremely infected with germs,'' she said. "Just because [the lens] is not in your eye, it doesn't mean it's not growing something. It's always good to discard your lenses.''