Snow blindness is a painful but temporary condition caused by the glare of the sun’s ultraviolet rays on snow. It can occur even on foggy or overcast days, and the symptoms may not appear for as long as 8 hours. The first symptom is difficulty in perceiving variations in the level of the ground. A gritty feeling develops in the eyes; then they begin to hurt when exposed to any light at all.
The best cure is prevention. Wear sunglasses that keep out ultraviolet rays. You can also protect your eyes with a mask made by cutting narrow slits in cardboard, plastic, or other material. Blackening your cheeks and nose with soot will reduce reflections.
If snow blindness occurs, the only treatment is darkness. Rest your eyes in a darkened room or cover them with patches or a blindfold until the pain and burning subside, usually within 12 to 24 hours.