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How to Buy Sunglasses
You may think the only thing you need to worry about when buying sunglasses is the style of frame or the color of tinting. But actually, there are other important characteristics of effective sunglasses that need to be considered.
Ultraviolet radiation can harm all parts of the eye, including the eyelid skin, conjunctiva, sclera, and cornea. That means that the whites of your eyes need protection, too. Here are some things you’ll need to keep in mind when you look for sunglasses.
Ultraviolet Light
Ultraviolet, or UV, radiation is that portion of the light spectrum that is beyond the shortest wavelength of visible light (which is violet). It can damage the human eye, which is why sunglasses are important. There are three types of UV light: UVA, UVB, and UVC.
UVA light is somewhat controversial – experts differ in their opinions regarding its role in harming the eyes, although it is universally accepted that UVA rays are what accounts for skin damage. If you are concerned about preserving your eye health, however, you may want to err on the side of caution and consider getting sunglasses that also block UVA light.
UVB light is the main culprit in eye damage done by ultraviolet light. UVB light does not go through glass, however, meaning the sunlight that comes through your window does not have the damage potential that outdoor exposure does.
UVC light is absorbed by the ozone layer of the atmosphere, and does not reach the earth.
What Constitutes a Good Pair of Sunglasses
When shopping for sunglasses, there are different kinds of lenses and with various levels of protection.
* Blue-blocking lenses are not blue in color; they are actually yellow or orange. The term “blue-blocking” refers to the light and color that is blocked when these lenses are worn. Blue-blockers are said to enhance vision because blue light wavelengths can cause things to look hazy. In other words, blue-blockers are more about clearer vision than UV protection.
* Polycarbonate lenses do a reasonably good job at blocking UV radiation, but their main function is to protect the eyes from physical injury. Polycarbonate is a tough, light lens material that can withstand hard impact.
* Photochromic lenses go from clear in low light to dark-tinted in direct, outdoor sunlight. Because glass filters out most UV rays, photochromic lenses do not darken very much when exposed to light through a window. They also take a bit of time to darken upon exposure to UV light, and their level of UV protection varies.
* Mirror-tinting or mirror-coated lenses offer protection from light in general, but they do not specifically block UV radiation.
If you are concerned about UVA rays, look for lenses that offer at least 95 percent protection from these rays. In order to protect the whole eye area, consider sunglasses with side panels, or wrap-around sunglasses, which are the most effective at blocking total UV radiation.
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