It helps your eyes relax instead of squinting all the time, Graves says, and that helps relax the rest of your body.

Even though Griffey has been a bit slow testing the amber lenses, he was counting the days until a Reds off-day so he could try his gray-green set on the golf course. The gray-greens--used in stationary sports; the ambers are geared for speed sports--allow golfers to better differentiate the shades of green on a course.

Golfer Justin Leonard has a pair of sunglasses with gray-green lenses, and he told Nike he is able to separate out every blade of grass. For baseball players, because amber blocks out blue light--visual noise to vision experts--red colors, such as a baseball`s seams, are accentuated.

There are medical advantages as well to wearing the lenses, which basically are soft contacts with a tint that has been scientifically developed. Although light can leak through sunglasses, through the opening between the frame and the eyes, performance-enhancing contacts sit on the pupils and better protect them from the sun.

Because baseball players are exposed to so much sunlight, some of them--Timlin, for one--develop a condition called pterygium that, essentially, causes a callus-type film to form on the cornea, leading to dryness in the eyes.