Pick different sunglasses of different light sources

Summer is coming, harmful rays of the Sun issued not only easy to burn our eyes, it is also the main culprit of senile cataract, selected a qualifying pair of cheap oakleys sunglasses is very necessary. Sunglasses assortment on the market, how to identify their usefulness and advantages and disadvantages of it?
Now many types of sunglasses, lens type can be summed up as 4 main types, namely paint color lenses, lenses, polarized lenses and photochromic lenses. Color sun lenses are lenses of the sunglasses of the most commonly used type, painted lenses are commonly used for sunglasses, polarized lenses best suited to outdoor sports (such as sea activities, skiing or fishing) to use when.
Consumers should select lens color under different light sources and occasions, many of the sunglasses on the tag will indicate 1, 2, and 3, which refers to the Sun lens shade of the color, darker series, and the higher the Sun more obvious.
Lens color variety, choose Brown best. Brown on any of the color spectrum is absorbed evenly, have good color vision sentience, where has chromatic aberration does not occur will only darken, ability to clearly distinguish between colors. Tan can filter as much blue light, improving visual contrast and clarity, even blinded by the light can see the object details, air pollution or wear better under foggy conditions.
Ophthalmologists reminder: choose cheap oakley sunglasses, the most fundamental is to guarantee everyone