Studies have shown that permanent damage to the eyes can result from prolonged exposure to the sun without adequate protection. Ultra violet (UV) light is the component of sunlight most responsible for eye damage. Excessive exposure, especially from light reflected from water, sand, snow or pavement, can produce a burn on the surface of the eye. Like a sunburn on the skin, eye surface burns are usually painful, but temporary. Of more concern is the cumulative damage of repeated exposure that may contribute to chronic eye disease. UV exposure can affect not only its surface, but also its internal structures (the lens and retina).
UV light is a risk factor in the development of pterygium (a growth that invades the corner of the eyes), cataracts (clouding of the lens) and macular degeneration (breakdown of the macula). Those at risk include people with lighter skin color, who spend a lot of time in the sun, those who live at high altitudes or near the equator, and those who take photosensitizing drugs such as psoralens (used to treat psoriasis), tetracycline, doxycycline, allopurinol or phothiazine. To protect your eyes from the sunlight, it is recommended that you wear a wide brimmed hat and sunglasses that filter out 99-100 percent of the UV light.
How do we choose sunglasses? The purpose of wearing them is for protection from the UV rays, not simply from the sunlight, so naturally the lenses should be guaranteed to prevent UV rays. Under no circumstances should anyone use dark glasses without UV protective lenses, because dark lenses cause the pupils to dilate, which expose the eyes even more to UV rays.
A good pair of sunglasses should curve towards the sides of the face to allow for maximum protection. As for the colors of the lenses, they can be chosen according to the wearer’s preferences. Gray will allow for the most natural vision, although clarity will diminish in dim lighting; green lenses will warp vision of natural colors; and brown or amber lenses will not change colors much, but will greatly help with clarity of vision.