It can also cause pterygium, which is connective tissue growth that stretches across the cornea. Both can impair vision. To prevent eye damage from high intensity light, Evans recommends wearing a wide-brim hat and sunglasses. Evans said sunglasses should provide 100 percent blockage. Not all sunglasses block out both ultraviolet A and ultraviolet B light.
Sunglasses generally have stickers that identify what rays they block out.
Evans is also concerned somebody would buy a pair of shades just because they are dark. One of the problems is they think if it's a dark tint that solves all the problems. A dark coating can be deceptive. A lighter tint of glass causes people to squint to prevent more sunlight in their eyes. Evans isn't so worried about those who wear contacts or glasses because they have regular checkups.