It's winter again in the Northern Hemisphere, and if your adventure travel is taking you to high altitudes, whether you're rock climbing, skiing, mountain climbing, or just headed up to snow, you need to be aware of the dangers of snow blindness.
Snow blindness, or photokeratitis, is caused by UVB rays burning your cornea. Prolonged exposure to sunlight, heightened by the glare off the snow, can lead to this disorder. The problem for many at high altitudes is that the symptoms of snow blindness may not show up until 6 to 12 hours after exposure. Those symptoms include pain, redness, tearing, swelling of the eyelids, a feeling of grit in the eyes, headache, the appearance of halos around light sources, hazy vision and temporary loss of vision.
Prevention is simple: A good pair of sunglasses or goggles with both UVA and UVB protection and side shields, as prolonged side exposure to the sun can be as dangerous as direct exposure. The difficulty is that removing those goggles, even for a relatively short period of time, to do something as simple as taking photographs, can lead to snow blindness. The primary treatments is to keep your eyes covered with patches for at least 18 to 24 hours. You should also use antibiotic eyedrops, and if you're planning on a multi-day climbing trip, be sure to bring along these prescription drops and an ophthalmic ointment in your backpack, along with patches and a cleanser. Put drops in your eyes and the ointment on the lids hourly.
Prolonged exposure to snow and sun at high altitudes can lead to solar retinopathy, a burn that damages the eye's retina. Solar retinopathy usually results from prolonged staring at the sun or looking directly at a solar eclipse, but it can also result from prolonged exposure to sun and snowglare while hiking or climbing. In mild cases of solar retinopathy, the eye can return to normal, but in a severe case the damage is permanent.
So whether you're hiking, climbing, or even piloting a small plane, keep those goggles on, and be prepared to treat any damage.