The sun changes the colour of our skin and harms it. The light of the sun can cause crystalline lens becomes harder and as result in cataract and irritation of sightnerves.
It is obvious that the good sunglasses must be used against the sun light. Since they will be part of our body, the material and the shape of sunglasses are important.

In addition they must match with the colour of the skin and hair and must be comfortable. If you follow the links next to the text you can get more information.