Kaleidoscope glasses
Sun glasses are one of protective eyewear type that is designed to prevent high-energy UV light and bright sunlight from discomforting and damaging the retina and eyes. (The New Partridge Dictionary of Slang and Unconventional English. Partridge, Eric, Tom Dalzell, Terry Victor). In the early 20th century, they were also known as sun cheaters (American slang).
The United States Environmental Protection Agency (EPA) developed the ultraviolet Index, and to protect your eyes from harmful solar radiation, sunglasses should block up to 100 percent of ultraviolet rays. High UV protection glasses don't have to be expensive. The difference is usually in the quality of the lens: when you buy a more expensive pair, you will be getting a higher quality lens that will provide a clearer, sharper, more pleasing image with less distortion. UV light is in wavelengths UVA (up to 400 nm) and UVB radiation (290 to 320 nm), both can be harmful to your eyes.
One of important features of your a pair of sunglasses is protecting your eyes from UV light from the sun. Shades which do not filter out UV light can actually cause more damage to the eye than no sunglasses at all. Eyes behind sun lenses dilate and more UV light reach the retina, unprotected exposure to UV light can lead to serious eye problems. So when buying a pair of sunglasses, look for the percentage marking of ultraviolet blocking. Now many a pair of sunglasses block 99-100% of ultraviolet light
From 10 a.m. until 2 p.m. the sun is high and UV light is the strongest Ultraviolet rays are also stronger at high altitudes and against the reflective surfaces of snow and water. Even if the sky is cloudy, Ultraviolet may be dangerous for your eyes and you should use protective a pair of sunglasses. Even though shaded areas reduce Ultraviolet exposure, your eyes can still be exposed to rays that bounce from buildings, roads and other surfaces.
When choosing sunglasses, better to invest in wraparound frames, they limit sunlight more effectively; protection of UVA and UVB rays should be 99 to 100%; gray or brown are the best for color recognition. It is important to understand, that UV protection and darkness are not the same. A pair of sunglasses are especially necessary for people with macular degeneration, cataracts, etc.
Polarization blocks glare, a pair of sunglasses with a special polarising film absorb horizontal light waves Having this chemical film on polarized sunglasses, you are able to see more clearly. Polarized sunglasses have been popular for years with boaters and fishermen who need to reduce reflected glare from the water surrounding them.
