People buy sunglasses for different reasons. Somedo so hoping it will improve their appearance or make them look like a Hollywood movie star. Others wear dark glasses to conceal their identities while a few purchase them simply for fun.
The majority of those who invest their money on a pair, however, are not only making a fashion statement. Their main concern nowadays is protection from the harmful rays of the sun.
Manufacturers who realize this are not making things easy for the consumer. They offer all kinds of lenses coated with sweet promises to catch the buyer's attention. But does it really matter which brand you buy? Are all sunglasses the same? Do they give the user any protection at all? More importantly, should you wear them in the first place?
Ophthalmologists say there is no need to wear sunglasses every time you step out of your house since the low levels of infrared rays in daylight are harmless. Furthermore, the eye has a number of built-in defenses. The cornea is a tough membrane that shields the eye from most of the ultraviolet (UV) light entering it. Even if UV rays damage it, the cornea quickly repairs itself and no harm is done.
"Under extremely bright conditions, such as sunlight or snow, prolonged UV exposure can overwhelm the cornea's repair processes, causing painful snow blindness. Even so, the cornea will usually recover completely inaday or two," according to the editors ofConsumer Reports.
The lens, the portion of the eye that lies behind the pupil, also acts as a barrier to sunlight, absorbing all UV rays that somehow pass through the cornea. This protects the light-sensitive retina at the back of the eye from damage.
When you stay too long in bright light, however, that's another story, Sportsmen, fishermen, construction workers, farmers, travelers and those who spend a great deal of time outdoors may suffer from UV ray damage later. This comes from two kinds of UV light: UVA which has long wavelengths, and UVB which has shorter wavelengths.
Of the two, scientists say the most damaging is UVB which causes cataracts and eventually blindness. One study of fishermen in Chesapeake Bay published inThe New England Journal of Medicineshowed that constant UVB exposure increases cataract risk threefold. The risk becomes even greater with the depleting ozone layer, earth's natural defense against UV radiation.
"Every one percent decrease in ozone inflates cataract rate by 0.6 to 0.8 percent. So if 10 percent of the ozone disappears, this could mean up to 2.8million cataract cases in the next century," warned Jane Lewis inLongevitymagazine.
"The chief worry about UV damage centers on the lens of the eye. Recent evidence suggests that chronic, lifetime exposure to UV contributes to some types of cataracts - opaque regions in the lens that interferes with vision. Numerous studies have found that people living in high-intensity UV areas such as the equator have a higher incidence of cataracts than people living where UV is less intense. In addition, lab animals exposed to high-intensity UV easily develop cataracts,”Consumer Reportssaid. (Next: Other risk factors for cataracts.)
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