Wearing sunglasses is an effective way to prevent ultraviolet rays from damaging the eyes. However, not all sunglasses have the function of preventing purple lines. Sunglasses can be divided into glass lenses and polyester lenses in material. Some imported high-grade sunglasses use special optical glass lenses to protect against uv rays. At present, most of the sunglasses on the market are polyester lenses and polyester lenses are divided into optical lenses and non-optical lenses. The optical lenses for uv protection is very difficult to guarantee the optical lens because through special processing for uv protection also can reach 100% using optical lens sunglasses on clearly marked "UV400" consumers should pay special attention to identify them. And uv protective effect of lens has nothing to do with the color of the lens without optical processing of dark lenses can't effective uv protection and transparent optical lenses can also with about 100% in uv protection. Choose lens to should choose moderate sunglasses according to the face shape size too small cannot cover the whole protection effect of the eye is limited and lens is too big affect beautiful again. Foreign experts also believe that the protection of ultraviolet rays should be grabbed from the doll, but attention should be paid to the choice of light, safe sunglasses for children to avoid causing unnecessary harm.