The types of sunglasses is recommended

Most sunglasses to protect our eyes from the harmful effects of the sun. The label on the sunglasses it is usually possible to prevent ultraviolet radiation and other types of natural radiation. It is important to know what kind of protecting our eyes need light, and what kind of light is not necessarily harmful. Recommended reading: outdoor brand sunglasses classic block 99% of the ultraviolet (uv) you should always buy has the function of sunglasses. Long-term exposure to ultraviolet light (in the sun UV） Radiation is associated with cataract and eye growth, including cancer. Compared with the UVA radiation, UVB radiation is considered more dangerous to eyes and skin. Plastic and glass lenses are absorbed some ultraviolet light, but in the process of manufacturing by adding chemicals into the lens material or coating with special lenses can improve the absorption of ultraviolet rays. Looking for sunglasses can block 99% or 100% uv. Some manufacturers label says 'ultraviolet absorb up to 400 nm. This is the same as 100% uv absorption. Ground and polished some over-the-counter glasses after grinding and polishing, in order to improve the quality of the lens. The grinding and polishing of non-prescription lenses won't hurt your eyes. Shock all sunglasses must conform to the federal food and drug administration ( FDA) To be on the safe side and the impact of the standard. No lens is really strong, but plastic lenses are less likely than the glass lenses broken when struck by ball or stone. Most non-prescription lenses are plastic. Polycarbonate plastic sunglasses, used in many sports, particularly tough, but they are easy to scratch. If you buy the polycarbonate lenses, please find a scratch-resistant coating of the lenses. Polarization of polarized lens cut the reflected glare - Sunlight reflected from smooth surface, such as roads, Windows and chrome plated surface or water. They are especially useful for driving and fishing. Polarization has nothing to do with ultraviolet absorption, but now many polarized lenses with uv blocking matter together. Check the label to ensure that the lens provides maximum uv protection. Dark medium lens for everyday wear, but if you use glasses under the condition of very bright, please select a darker lens. Didn't tell you the lens color and dark ability to block ultraviolet light. To change color to light color lens under strong light automatically dimming, under the weak light gets brighter. Most dimming occurs in about half a minute, it will take about five minutes and lightning. The photochromic lenses have uniform or gradient color. Although the photochromic lenses may be good ultraviolet absorption sunglasses ( This advantage label must, also) , but they need time to adapt to different light conditions.