You can not see them, but ultraviolet (UV) rays-primarily type B-can damage your eyes. Spend an unprotected afternoon in the sun and you risk getting a temporary burn of the cornea which can make your eyes feel dry, gritty and sore for several hours. And long-term sun exposure can lead to cataracts and other age related eye disorders.
The best way to protect your eyes is Invest in a wide-brimmed hat (which will shield your eyes from about 50% of the UV they would normally get) and a good pair of sunglasses. Choosing the latter is somewhat more complicated, since there are currently no enforceable regulations for lens effectiveness or accuracy in labeling.
For the best UV protection, look for glasses that black 99% of UVA and UVB.
Make sure lenses are dark enough. For optimum, they should screen out at least 75% of visible sunlight to check the tint, try them on and stand a foot or two away from a mirror. If the lenses are dark enough, you would not be able to see your eyes.
Opt for a wraparound design; it blocks peripheral light and offers the most protection.
Be wary of vague or blood labels, such as “blocks harmful UV” (even plain glass blocks some UV) or “offers 100% UV protecting” (nothing offers 100% UV protection)
Don’t judge a lens by its price tag. Cost is not a good indicator of lens quality or UV protection.
Give glasses the distortion test. Hold them at arm’s length and look through the lenses of a straight vertical line in the distance, such as the edge of a door. Slowly move them from side to side across the line. If the line distorts, sways, curves or moves, the lenses have imperfections.
Make sure the lenses don’t modify colors. (You should be able to distinguish traffic light colors. (You should be able to distinguish traffic light colors, for instance). As a rule, gray lenses offer the truest hues; green and brown are nearly as good. Avoid blue or purple, which distort colors.
Tailor your glasses to your hobbies. If you spend a lot of time around the water, opt for a polarized pair-it will reduce glare from sunlight that bounces off the water. Mirror coatings are ideal for the super-intense reflection you can get from snow. For racket sports, consider shatter-proof polycarbonate lenses.