See the Light: UV Ratings That Are Good For You

Do you think you've seen the light? Not all of it. In fact, some of the most harmful light rays are the ones you can't see. Ultraviolet rays, the most damaging of the light spectrum, are outside of our perception limits. Because we can't see this level of light, we ignore it. But it still fries our eyes.

Violet is the highest-energy color we can see. It's literally at one end of the rainbow. (Red, the lowest energy color, is on the other end.) All light contains energy, and our eye heals itself from the day-to-day damage - in fact, the eyes are the fastest healing organ of the body. But high energy ultraviolet light - the same light you block with suntan lotion - can overwhelm the naked eye, causing harm it can't keep up with.

So how do you guard against something you can't see? Easy: this is one time you can trust the experts. Sunglasses designers reliably follow industry standards which measure how much light their lenses filter out. Sunglasses vary greatly, and there are two measures to check. UVA is the ultraviolet closest to our visible light. UVB is farther, and as you now know, it carries more energy and thus more threat.

Cosmetic glasses filter up to 60% of visible and UVA light, and up to 95% of UVB. They're fine for a trip to the mall or a fashionable pose, but they're not enough for intense or prolonged exposure. You don't want to be studying sun spots with these.