Dark glasses are not the only solution to the threat of snowblindness on snow and ice. Although I carry sunglasses, I wear them infrequently, mainly on blindingly sunny late-spring days on icefields. The rest of the time, I find them unnecessary. Instead, I use ordinary, clear prescription glasses that are UV-coated. It’s ultraviolet rays, not brightness, that causes snowblindness.
Some beginners fail to realize that you can get snowblindness even on murky overcast days, when one doesn’t feel the need for sunglasses. I’ve also heard of people who’ve suffered snowblindness while wearing cheap sunglasses that didn’t block enough UV.
Sometimes, you don’t need protective glasses at all. In Labrador, the snowblindness season starts in early February. In the High Arctic, it’s early April. Here in the Canadian Rockies, it’s mid-January. Before that, the winter sun is too low to sunburn the cornea, which is what snowblindness is. It also makes a difference whether you’re traveling with the sun at your back or in your face. Altitude is also a factor.
I’ve often traveled during the transition into the snowblindness season. At first, not wearing glasses feels fine. Then one day, the eyes begin to feel tired by late afternoon. That’s the signal to start using UV protection.
You can choose UV coating as an option when you order prescription glasses. Photo: Jerry Kobalenko
Why do some of us feel the need to wear sunglasses often, and others don’t? One theory: A few years ago, I was at the optometrist getting my eyes tested for a new prescription. He kept trying to photograph the inside of my eye, but the images all came out black. Apparently, my pupils closed down too much during the flash.
Different people, the optometrist explained, have different minimum pupil diameters. I have what he called pinpoint pupils. My pupils respond to bright light by becoming so small that the light rarely bothers me. I’d like to wear aviators once in a while, because I imagine, probably incorrectly, that they’d make me look cool. Unfortunately, they also make the world feel unnecessarily dark.
