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The glass version of photochromic lenses was developed by Corning in the 1960s. Plastic versions of this type of lenses is also available. They are commonly meant for commercial usage. Such sunglasses benefit regular users of eye lenses a lot. It prevents them from carrying two or three pairs of eyeglasses while going out. You might be wondering how oakley sunglasses sale sunglasses change their color on getting exposed to UV rays. To learn about this along with some advantages and disadvantages of photochromic sunglasses, keep reading.

The reason behind the ability of the photochromic sunglasses to change their color from light to dark is its molecular structure and the effect of light on it. The polarized photochromic sunglasses contain millions of molecules of substances like silver chloride or silver halide. These molecules are transparent to visible light or in the absence of UV light. When they are exposed to UV rays, a chemical reaction take place which causes the molecules to change shape. The changed molecular structure absorbs portions of the visible light. This causes the lenses to get darkened. Therefore, polarized lenses are quite effective.

The number of the molecules which change shape differs from the intensity of the UV rays. When the photochromic sunglasses are no more exposed to UV rays, the reverse chemical reaction occurs. The sudden absence of UV light results in the snapping back of the molecules to their original shape. This, in turn, results in the discount oakley surfing sunglassesloss of their light absorbing properties. In both the direction, the entire process of change in the molecular structure takes place quite quickly. The darkening of the glass is directly proportional to the intensity of the sunlight.