(1) lens
One of the easiest ways to judge the quality of a lens is to shake it back and forth in front of your eyes to see if the object moves with the lens. If it is, it means that the lens is uneven and belongs to unqualified lens. Of course, this is for flat mirrors, but if it is myopia sunglasses, it is not very accurate.
(2) Color
In addition to entertainment, if it is really to prevent ultraviolet rays, it is better to buy sunglasses in Ray-Ban Grey, Ray-Ban Green and Blue Grey. The lenses really block light, because these relatively soft colors will not change color when looking at nature, which is especially suitable for car owners, because it will not affect their recognition of traffic signals such as traffic lights.
(3) ultraviolet index
For sunglasses, the ultraviolet index, that is, the effect of filtering ultraviolet rays, is a very important standard. At present, the ultraviolet index of most sunglasses is between 96% and 98%, and dark lenses are better than light lenses. Generally speaking, a UV index of 100% is impossible. If a manufacturer claims that his sunglasses have 100% ultraviolet filtering effect, he is a bit boastful.