Sunglasses UV index is what
The UV index: for sunglasses, UV ultraviolet index is the filter effect, 280 - should be eliminated 400 nm this band light. At present, most of the sunglasses UV index between 96% ~ 98%, dark lenses must be better than the light color lenses. Into the earth's surface in the sun all 5% of uv light, ultraviolet light skin, the eye is harm to human body. Between 280 and 320 microns of wavelength UV ultraviolet - B of keratitis can cause eye and skin cancer, UV wavelength between 320 and 380 - C ultraviolet ray can make people easy to cataracts and retinal burn. The sunglasses with a UV - 400 logo shows that can filter out harmful rays wavelength within 400 microns, and can stop more than 98% of human exposure to the sun's ultraviolet rays, thus has better protective effect. Block the light by quantity depend on the color of the lens, the deeper the color the more you will block the light rays is processing the lens in the liquid state to absorb ultraviolet light raw materials which have the effect of rays, regular sunglasses are commonly 100% uv protection that is UV400. Ordinary optical resin lenses are generally UV360 ~ 380, unless there are special instructions to prevent UV400.
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