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Sunglasses - Cognitive Information |
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| Date Added: March 20, 2010 03:35:00 PM | |
| Author: | |
| Category: Shopping: Health | |
At present sunglasses are worn all year round. Designer sunglasses represent not only a stylish accessory, they are essential to protect your eyes from ultra-violet radiation. The penetration of ultra-violet rays into the eyes may cause various ocular illnesses. Staying under the direct sunlight, in summer or in winter, is very harmful for your eyes. Human organism was adapted to protect the eyes from bright light – iris-contraction and squinting reflexes reduce the penetration of ultra-violet rays into the eyes. But the UV-rays are active on an overcast day as well, so the mentioned natural mechanisms are not sufficient for full protection. That's when wearing sunglasses goes to the rescue. Modern sunglasses with ultra-violet cover characteristics represent an effective device for individual shielding against the ultra-violet rays. For example, wide-brimmed hats give just 50 per cent ultra-violet shielding and are not efficient against light reflected from horizontal surfaces such as grass, water and snow. That is the reason why your vision is misting and it is so difficult to drive a car when the sun shines brightly. Eyes irritation and headaches are momentary symptoms if you're under the sun rays for a long period of time. What is more, all this may bring to more serious diseases with time. Sunglasses with good ultra-violet protection coat in their turn give high level of sun shield and better eyesight in bright sunlight. The variety of lenses with ultra-violet cover characteristics is great, so you'll probably need a guide to make a decision. First of all, take into account that level of darkening and color have nothing to do with the efficiency of ultra-violet radiation protection. You should pay attention to these characteristics when choosing the type of lenses depending on your activity. In this way, middle-dark lenses are ideal for wearing everyday when at the same time being under bright sun for a long period of time requires darker lenses. Sunglasses with polarized lenses are applied for driving or for water activities as this type of lenses diffuse the light reflected from smooth surfaces. For producing prescribed sunglasses manufacturers apply photochromic lenses because optical transmission in these lenses is about 25-80%. There are also lenses of different colors used for various activities. In such a way, grey lenses are preferred by decorators and painters. Green and brown lenses improve the range of contrast. Numerous followers of the sportive style give their preference to yellow lenses. Doesn't matter what type of lenses you choose, make sure that your sunglasses are with good anti-UV cover. |
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