There's more choosing shades than how good they look on you. Your sunglasses should keep damaging sunrays away from your eyes.
By Jean Lawrence
Reviewed By Michael Smith
Do you love how cool your sunglasses make you look? If you really want to be comfortable in the glare and protect your eyes -- and your children's eyes -- from future cataracts, there is more to selecting sunglasses than mere "coolness" (desirable as that is).
Although the human body is aces at replacing some damaged cells, the cells in the lens of the eye are never replaced. Damage from ultraviolet and (to a lesser degree) infrared rays can build up over a lifetime and lead to cloudy areas on the lens of your eye called cataracts. It's hard to see through cataracts, and they often must be removed surgically. Macular degeneration, an eye condition resulting from damage to the retina, also may be accelerated by too much unfiltered sun blasting the retinas.
"The thing you want to guard against mainly is ultraviolet rays," explains Lee Duffner, MD, professor of ophthalmology at the University of Miami and spokesman for the American Academy of Ophthalmology. "You want to filter as many of these as you can away from your eyes." Most sunglasses, coated with UV blockers, block the ultraviolet B rays, but the cheaper ones may cheat a little on ultraviolet A. Examine the label. (Some contact lenses also block UVB -- ask your eye doctor.)
Besides UV, brightness is an issue. What people don't realize, Duffner says, is that going from inside to outside involves confronting light thousands of times brighter than that going into the eye the moment before. Brightness is a comfort issue -- it's uncomfortable to go into the sun from the shade and to have undimmed light flowing into your eyes.
So the darker the lens in your sunglasses the better? "Clear glass transmits 90% of light, Duffner says. As the glasses get darker, less and less light goes through. Lightly tinted lenses let in 75% to 80% of light, Duffner says. Military standards specify that only 15% of light should penetrate. "You can still see very well with 10% to 12% of light only," he notes. "I recommend glasses in the 20% range."
Duffner says the overall best color to get is gray. "This absorbs light across the spectrum equally."
Eight percent of men and almost no women have color deficiencies (which used to be called color blindness). "Depending on your deficiency," Duffner explains, you need to select a certain tint of sunglasses. "Bronze is not good for men with a green deficiency. Green is not good for anyone with a red or green deficiency. Gray is safest for men." Women should go with gray, green, or brown, he adds.
Rose-colored sunglasses. Are they a good way to see the world? "Pink isn't a good color for anyone to get," Duffner declares.
There are amber-colored lenses called "blue blockers." For a while, these were recommended for tennis players. "These absorb not only ultraviolet, but all blues in the color range," Duffner says. "Some people say this makes for sharper vision, but they did a study and showed that they do not block UV very well and may cause the pupil to dilate and let in more ultraviolet."
Another popular option is "polarized" sunglasses. "These are very helpful against reflected light (such as on water, snow, or the road)." The light particles called photons travel in a wave form, Duffner explains. Polarized sunglasses, which have a protective layer bonded on much like the tinted film put on car windshields, admit only vertical waves. Since most of the reflected waves are coming in horizontally, those are blocked.
As for the mirror sunglasses popularized by highway patrol officers, Duffner is skeptical. "These aren't really good protectors," he says. "If you are worried about UV, these should not be your first choice."
How about those gradient glasses that are dark at the top and then lighten toward the bottom? "The most bothersome (reflected) light comes from the bottom," notes Duffner.
Parents who slap some sunglasses on their babies have the right idea, according to Steven J. Lichtenstein, MD, Louisville ophthalmologist and chairman of the American Academy of Pediatrics' section on ophthalmology. "Every human should wear sunglasses," he says. "I see young adults with cataract changes all the time."
Wearing sunglasses is especially important between 10 a.m. and 2 p.m. Even children with dark eyes, which provide partial protection, should wear them.
Like adults, kids who wear prescription glasses can get prescription sunglasses. "Or clip-ons," Lichtenstein adds. "They make those for kids' glasses." Duffner recommends wrap-arounds for people who are out a lot, although these aren't so great in prescription form.
For kids, you want wearability. "Something comfortable, something they will keep on," says Lichtenstein.
Glass or Plastic?
Glass is adequate at blocking UV, according to Duffner. But polychromic sunglasses -- glass lenses that get darker as you encounter brightness -- are the gold standard. "Those really work," he says, but glass sunglasses are heavy, despite being long-lasting. "I had a patient today," Duffner laughs, "who told me he had been wearing the same polychromic glasses for 24 years." Glass doesn't scratch as easily as plastic.
How about driving? "Sunglasses can cut glare," Duffner says. "But never wear them at night." So much for being cool.
Originally published May 22, 2003.
Medically updated May 13, 2005.
SOURCES: Lee Duffner, MD, professor of ophthalmology, University of Miami, spokesperson for the American Academy of Ophthalmology. Steven J. Lichtenstein, MD, Louisville ophthalmologist, chairman of the American Academy of Pediatrics' section on ophthalmology. University of California Davis.
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