Snow blindness is so incredibly painful that no one who has had it will ever willingly run the slightest chance of getting it again. If you’ve ever wondered whether you’ve had it, you haven’t! And, unlike many uncommon ailments, it’s extremely easy to describe to someone who knows nothing about it: If you were to lie down, open your eyes wide and then have someone put a teaspoonful of sand into each of them (and see to it that it remained there for at least 24 hours) this experience would give you a very accurate idea of what it feels like to be snow-blind.
Snow blindness is temporary damage caused by ultraviolet light to the delicate outer layer of the eye—the incredibly thin corneal epithelium. Luckily, although it can be excruciatingly painful, the damage is never permanent and discomfort rarely lasts more than four or five days, even in the most severe cases.
Ultraviolet light is invisible, so the amout of visible glare on snow or beach has no direct relation to the amount of danger of snow blindness, though glare alone can tire one’s eyes and result in a severe headache. Ultraviolet rays are filtered out quite effectively by dust and haze, so the clearer the weather and the higher you climb, the more UV you encounter. The higher the sun climbs in the sky, the less dust and haze its light must pierce to reach you, hence the lack of danger in the midwinter when the sun is never high except in the tropics. You don’t have to look at the sun (or even near it) to be affected. The atmosphere has a miraculous way of dispersing these extremely short wavelengths of light so that at times the sky can contain three or four times as much UV as direct sunlight!
Except in relatively high altitudes (above 9-12,000 feet, where the dense haze of the lowlands is usually left behind), you aren’t liable to get snow-blind unless you get a double dose of this UV energy, reflected from the surface of the snow as well as from the sky itself. Incidentally, if you’ve once been snow-blind you need be neither specially worried nor overconfident. Unlike the skin, your eyes won’t tan or develop a resistance to UV, for no matter how many times you’ve been on a glacier or up a peak, your eyes will be just as susceptible tomorrow as those of a man who has never seen a snowbank in his life. Some people appear to have a very high tolerance to UV light, others must protect their eyes with special care. No one is immune.
Unfortunately, as in the case of sunburn, you never know when you are becoming overexposed to UV until it is too late. A number of short exposures within a single day are just as dangerous as if they had all been added into a single long exposure. Except in the case of extremely intense exposures (as in watching arc welding with no goggles), there is a "latent” period of several hours during which no pain is felt and your eyes appear to be virtually normal, though vision may slowly become cloudy and indistinct. Then things begin to happen fast. First, you feel slight irritation; then, as this increases, your eyes begin to cry, become extremely bloodshot, then stream uncontrollably. Within an hour after these first symptoms, your eyelids are red and swollen to a point where your eyes cannot be either opened or shut and they feel as if they are brimful of sand. The slightest light is painful (even through the closed and swollen eyelids) and every single involuntary effort to blink results in an intense jab of pain. This may last only a few hours or, as in a very severe case which I experienced myself in Alaska in 1933, it may totally incapacitate one for four or five days. Furthermore, the pain is so intense and constant that sleep or rest are virtually impossible. Even the strongest persons are utterly exhausted physically after even a relatively short siege of real snow blindness.
More bad news: Once you’ve got it, there is almost nothing that can be done to produce real relief. Do not use even the weakest local anaesthetics except when administered by a highly trained physician, as they may seriously slow down the healing of the delicate epithelium which has simply been sunburned. Cold (not warm) compresses and total darkness are easy to provide and yield some comfort. Every conceivable effort should be made to prevent scratching or other physical harm to the eye or lid, as a result of rubbing, or incessant touching with your hands— something which the incessant pain makes it almost impossible to prevent unless the eyes are kept constantly bandaged or covered with compresses. An occasional plunge of the whole head in cold water always affords real, but brief, relief. When an experienced doctor is not present, these simple rules plus the passage of time will do the job, as professional care is not needed for snow blindness, if you don’t further damage or infect your eyes with your own hands during the first few hours of intense pain. Luckily, the back of the eye (retina) is never affected, as the cornea absorbs all the UV before it gets there. The iris, which cuts down the amount of light entering the eye (like the diaphragm of a camera) lies behind the cornea and in front of the lens. Therefore the normal and involuntary closing of the iris in intense light does not reduce the danger of snow blindness at all, as it only protects the part of the eye which is behind the affected region.
What can you do to prevent all this? Just buy a good pair of sun glasses or goggles which will eliminate all the ultraviolet light—and wear them constantly. It’s as simple as that. The darkness of glasses has in itself no bearing on their capacity to filter out the UV, even though this will reduce tiring glare. High-grade sunglasses (like American Optical’s Rose Smoke lenses) do two things: they include an invisible dye which completely eliminates the UV, and they also have an inert but visibly colored dye which reduces the glare about 80 percent, allows the iris to open more, and helps to restore normal relaxed vision.
Large glasses which are designed to rest well up on the nose and near the face are better than goggles, as they permit better circulation of air around the eyes and minimize the annoyance of "fogging.” Glasses of standard size and set forward on the nose do not give adequate protection in intense conditions, particularly in high altitudes on snowfields or glaciers. Goggles are only best in certain special situations—like ski racing—but do not afford any better UV protection than larger glasses, as all that the sides of the goggles accomplish is to prevent excessive circulation of air, snow, or dust around the eyes.
Snow-glasses are as essential a part of your skiing or climbing equipment as bindings, wax, rope, or ice axe. Buy good ones and wear them.
Note: This article is the result of 30 years of experience on high mountains and glaciers, afoot and on skis. The author has had one acute case of snow blindness himself (23 years ago) so he knows whereof he speaks. Practicing these simple common sense rules neither he nor any other member of his many Alaskan expeditions has ever had even a mild case since then. For further scientific details see: ''Clinical Neuro-Ophthalmology,” by Frank B. Walsh, Baltimore, 1947, pp. 1276-1279; "Textbook of Ophthalmology,” by Sir Stewart Duke-Elder, London, 1954, vol. 6, pp. 6510-17; note by S. Holth, on "Goggles vs. Glasses,” in Ophthalmoscope, February 1955, p. 71.
*This article, in slightly different form, was printed in Sports Illustrated, 1957, and is here reprinted by special permission. Copyright, Time, Inc. Snow blindness is exactly the same malady as "Klieg-eye” or "flash-eye” which come from overexposure to UV from arc lights in studios or during welding if protective glasses are not worn.