Protection from ultraviolet radiation.

The blue-violet part of the light spectrum is most dangerous to the eyes, as it easily passes through the cornea and lens, and its excess is causing to damage of a retina. Children, the elderly, patients with eye disease who had undergone surgery on the retina or the cornea (eg, laser vision correction), and without exception, blue-eyed blonds and representatives of Caucasoid type to suffer from bright sun in the spring and especially summer. But for the other it is not safe. Craftiness of excessive exposure to solar radiation consist in that person does not see or feel its, but over time it making itself felt.

Statutory requirements for sunglasses are regulated by national standards. According to them, there are three main groups of sunglasses - cosmetics (Cosmetic), conventional (General) and the glasses high degree of protection (High UV-protection). Cosmetic lenses - pink, purple, green and blue - are ineffective to protect and serve only as an accessory. Lenses high degree of protection required for high mountains and polar regions, equatorial-tropical regions, and conditions of ozone anomalies. And finally, lenses General - this summer lenses that meet the requirements of Europe and North America. Sunglasses with high level of UV protection can be with lenses of neutral, brown, greenish-brown color, but not with blue and purple. When choosing sunglasses, pay attention to their labeling. "UVA" and "UVB" shows the percentage of protection from ultraviolet rays (type "B" is considered the most harmful, and type "C" absorbed by the atmosphere). The designation "UV-400 nm" means that the lenses protect eyes from all UV light with wavelengths below 400 nm (the average length of light waves, reaching up to our eyes, - 290-380 nm). If the figure is less than 400, then still part of the rays is passed. Information about protection against infrared radiation does not write on the sunglasses usually and, as a rule, it is implied by default. Some lenses do it better than others, such as lens with polarization.

  

FYI: Every day the National Weather Service calculates the predicted UV Index for the next day in each area of the U.S.

Everyone knows to wear a hat or sun block to protect against ultraviolet radiation. But most overlook the importance eyewear play in protecting their eyes against ultraviolet harm.