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About SunglassesFind the best protection |
By Stefan Anitei, Science Editor
8th of May 2008, 12:39 GMT
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Sunglasses are defined as an ophthalmologic medical article made of frames and lenses, meant to diminish the amount of sunlight; however, they do not accomplish any sort of optical correction. Their main goal is to protect the wearer against excessive sunlight.
In many cases, we pay exaggerated amounts of money for
the name of the brand that made the sunglasses. As a rule, though, cheap or very cheap sunglasses are of lower quality and that happens primarily because a popular brand can't afford to have its image sullied by selling low quality products. Even if sunglasses may seem better than nothing at all, the truth is far from that: interposing colored lenses between the eye and sunlight determines the physiological dilatation of the pupil. If the lens does not offer a sufficient protection, the fact is that more light enters the eye, including ultraviolet and infrared rays, which are harmful, through the dilated pupil. There are several theories that explain the affections of the crystalline lens and the cataract through these radiations.
Cheap plastic lenses are harmful because they can distort the image of the objects reflected on their surface and can sometimes have an undesirable and unprescribed dioptric value. For the record, sunglasses should have a marking with their degree of protection on the frame, which any interested buyer can see at the moment of purchase.
Glasses, no matter their type, should also fit your physiognomy and be comfortable. In many cases, fashionable or trendy sunglasses may not match the physiognomy of the wearer, conferring to him/her a rather comical look. Even if sunglasses do protect 100% against UV, they cannot dampen the brightness of a water surface or of a road while driving. In order to diminish this, you should use specially made lenses that polarize the light.
Which is the best color for sunglasses, you might wonder? A few years ago, Americans preferred gray glasses, while Europeans brown ones. The gray absorbs all the colors of the visible spectrum, reducing light intensity without distorting the colors, an important fact when you need a precise perception of the colors (like in the case of pilots, drivers, spectators at sport games, and other categories).
Green lenses are the most effective in absorbing UV and IR radiation, but they make violet, blue, orange and red hard to distinguish. This color is recommended in situations where there is a large amount of reflected light that contains a lot of UV rays, like when spending the holidays in a tropical location. The psychological effect of these lenses is refreshing.
Brown lenses absorb almost all UV radiation, and can be used in a moderately warm to cold environment, as they create a sensation of warm environment. For observing temperatures in furnaces, blue lenses are used. However, once outside, these lenses are of little use.
Yellow lenses absorb UV rays, violet and blue light, and are preferred when hunting (especially at the sunset) and driving in foggy conditions, but they are not useful against excessive light. Other colors (orange, purple, mauve) have no protective qualities but can be used for their trendiness factor nonetheless.
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