Studies have shown that excessive ultraviolet ray into the ordinary frames, lens protection will reduce, will cause harm to the eyes.
Recommended reading: children's sunglasses uv protection is enough?
Surround type around the shape of the type of glasses can prevent light around framework and into the eyes, can protect your eyes from the harmful effects of the different angles.
The gradient lens gradient lens from top to bottom or from the top and bottom towards permanent shelter in the middle.
A single gradient lenses (
At the top of the darker, lighter at the bottom)
Can cut the glare from the sky, but you can clearly see below.
They are very useful for driving, because they will not make you in view of the dashboard to darken.
However, they decrease in snow-covered environment or the glare on the beach is not so good.
Double gradient lenses (
Shallow darker at the top and bottom, middle)
May be more suitable for the light reflected from the water or snow sports, such as sailing and skiing.
Suggest not to use double gradient lenses for driving, because they can make the dashboard appears bleak.
Mirror mirror finish coating is common lenses of various thin layer of metal coating.
Although they can reduce the amount of visible light entering the eye, but don't think they will fully protect you from uv radiation.
Block 90% of the infrared infrared wavelengths is invisible and generate heat.
Sunshine has low levels of infrared ray, the eye is a good way to tolerance of infrared light.
Some sunglasses manufacturers based on infrared protect health claims for their products, but the study did not show there is a close relationship between eye and infrared.
Blue block blue light is harmful to the eyes is still controversial.
Block all blue lens is amber, usually make your surroundings look yellow or orange.
Presumably, tonal make distant objects look clearer, especially in the snow or fog.
Therefore, amber sunglasses in skiers, hunter, boaters and pilots are very popular.