HashOut: 2007/09/30
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Get smarter on Sunglasses

Summer. The time when sunglasses are most used. Some glaring facts about them from eye doctors.
  • Not everybody needs sunglasses: most of us can tolerate normal sunlight unaided. Wear sunglasses if you constantly encounter dust, glare, wind, or prolonged exposure to intense sunlight. Wearing them at all times can reduce your eyes' tolerance to light, making even normal light seem unpleasant.
  • Spurious sunglasses can harm your eyes. Select a pair with a brochure or sticker that says "UV400" or "100% UV protection." But manufacturers often falsely make the claim, so it's safest to pay extra for a reputed brand. Shaded behind sunglasses, your pupils dilate. So glasses that are not UV-safe will let in excessive ultraviolet rays which cause cataracts, a gradual clouding of the eye's natural lens.
  • Glass colour has no bearing on quality or UV protection. But grey, light green or brown do not adversely affect our colour perception -- unlike yellow, red and other colours.
  • Plastic lenses being unbreakable and light are safer than those made of glass for games or diving, and for kids, Ask for "scratch proof plastic."
  • To test the optical quality of non-prescription glasses, hold them at half an arm's length and, with one eye closed, look through a lens at any object. If the object seems to move or wobble as you move the glasses, the lens has imperfections and may cause headaches. With a good lens, the object will stay as is.
  • Polarized sunglasses are best for cutting the glare -- suitable for driving, boating, beaches or snow.
  • Photo chromatic glasses adjust to UV -- a better choice for those who often wear sunglasses.
  • Don't encourage small children to wear sunglasses habitually -- they're likely to grow up unable to manage without them.
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