While buying sunglasses all of us think that it protects our eyes from high intensity light. So how they work in the protection of our eyes? Tinting of glasses determines the amount of light we are exposed to. The black and grey tinted lenses provide most of the protection to our eyes and color distortion is the least.
Sunglasses often have some kind of coating that filters the light coming to our eyes and prevents ultra-violet rays to enter which can be harmful for our eyes and allows the other wavelengths to easily cross the coating. It also protects eyes from the glare. Glare is a light coming from shinny objects water etc. this happens because light rushes from all directions and intermingle with each other and causes glare. The molecules of polarization of the light realign the waves and remove the glare from it.
A right color must be chosen for sunglasses like gold, amber, yellow.
Colored sunglasses stop the blue light and can cause blurred vision, green colored glasses filters a part of blue light and diminishes the glare. In a green or blue background purple or red color provides best contrast of objects and is mostly used water skiing.
To get more protection it is advised to get polarized sunglasses which almost prevent the entry of harmful glare while flat surfaces can result in glare. Small sized frame allows the light to enter from the sides which lessen its affect while large frame lenses give more protection to our eyes and also the skin around it.
So it is advised by doctors that we should wear U.V protected sunglasses of good company because other can harm your eyes instead of protecting. It is better to wear no glasses than to harm eyes with cheap ones. Theses glasses are coated by thin layer which forces our iris to open wider instead of getting smaller which permits more U.V rays to enter.