Blurry vision, burning, gritty-feeling eyes, swollen eyelids and headaches are symptoms of snow blindness, the medical condition known as photokeratitis. It’s a temporary but painful condition that occurs when exposure to ultraviolet rays creates inflammation on the surface of the eye.

“I’ve been on mountaineering expeditions where we had to actually help someone down off a mountain because they suffered snow blindness at high altitude,” said high-altitude mountaineering legend Ed Viesturs.

It happens to people when they don’t realize how bright and sunny it is, and they’re not wearing sunglasses. “Maybe you took your sunglasses off because you’re filming or you just forgot them for a while,” he said.


A team of sled dogs pulls a sled underneath sunny blue skies.


Light Eyes, Medication, Location and Season

Do you have light-colored eyes? Eye color can also affect your susceptibility to snow blindness; people with blue, green and light brown colored eyes are more vulnerable to photokeratitis. More than half of Americans have light-colored eyes, making snow blindness a significant public health issue.

Another contributing factor to photokeratitis sensitivity is the use of medications like antibiotics, antidepressants, ibuprofen, naproxen, statins, antihistamines, diuretics, diabetic and acne medication, each of which increases sensitivity to sunlight and vulnerability to UV-ray damage.

High altitudes also make a difference because the thinner atmosphere filters less UV radiation. According to the World Health Organization, UV levels increase by 10% to 12% with every 1,000 meters in altitude. Cloud cover, latitude and ozone levels are additional factors determining how much UV light reaches your eyes.

According to a study in the Journal of Postgraduate Medicine, when you compare summer in the Northern Hemisphere versus the Southern Hemisphere, the Northern Hemisphere is 1.7% farther away from the sun than the Southern Hemisphere, and the intensity of UV light decreases by approximately 7%. Quebec in the summer, for example, will have a lower risk of snow blindness than Madagascar in the summer.



Two high-altitude climbers roped together climb up a snow slope underneath a bright blue sky.


Climbers, Dog Sledders, Skiers and More

The effects of photokeratitis can be serious, especially if you’re in a place where clear vision is vital. In this past climbing season, Global Rescue assisted a member climbing in Nepal suffering from frostbite on her toes and snow blindness. Her condition triggered a helicopter evacuation from Mount Everest. Another Global Rescue member needed to be carried to safety by Sherpas from a Himalayan mountain due to the pain in both eyes from the severity of her photokeratitis condition. A third member climbing at high altitude on Annapurna lost his sunglasses and needed rescue when eye pain from snow blindness ended his expedition.


[Related Reading: Snowblind in the Himalaya]


Remember racer Doug Swingley, who removed his goggles during the 2004 Iditarod sled dog race for a quick look ahead? His vision became extremely blurry, according to the American Academy of Ophthalmology, and he had to leave the race to receive medical treatment.

Ski instructors frequently come across ill-equipped learners who are missing gloves, layered clothing and eye protection. When the cold or snow blindness brings on the discomfort of numb fingers or blurry vision it results in tears, especially with children.

Tyler Hagan, a Global Rescue sales associate and former ski instructor, improvised a resourceful way to fix the problem. “I made sure to bring the kids to the nearest lost and found to scrounge the essentials and continue with the day. Later, I’d counsel the parents to make sure their children had appropriate equipment for next time,” he said.

It’s not just the snow that can cause photokeratitis. Water and white sand are also reflective, so spending a day on the ocean or lake also puts you at risk. Your eyes are prone to sunburn from a direct hit from the sun combined with the reflection of the sun from the water or sand.

Fortunately, snow blindness is not usually permanent and it’s often short-lived. The symptoms are caused by temporary damage to the cells on the surface of the eye. If there is vision loss, it typically resolves in 24 to 72 hours.


A woman backcountry skis across an open peak beneath sunny skies.


Recovery and Prevention

Just like a skin sunburn, by the time you notice the damage to your eyes, it’s too late. To aid recovery, a doctor may prescribe eye drops or pain relief tablets to make the eyes more comfortable while they heal. A doctor may also recommend:

  • Staying indoors to let your eyes heal before going back outside.
  • Keeping eyes well moistened with artificial tears.
  • Placing a cool, damp washcloth over closed eyes.
  • Removing contact lenses.

Today, outdoor adventurers can stop by a sporting goods store to purchase either polarized, mirror-coated or photochromic-lensed (lenses that darken upon exposure to light) sunglasses, glacier goggles or snow goggles.

Wear sunglasses that block out 100% of UV rays whenever you plan to be outdoors for more than three hours at a time. Remember reflective glare from sand, water and snow can still harm your corneas even when the weather is overcast.

As a rule, the view may be gorgeous but please keep those goggles or sunglasses on at all times.


How Global Rescue Can Help

Traveling to a sun-drenched or snow-covered location? Sign up for a travel protection services membership. Whether you are on the top of Aconcagua or in the middle of the Indian Ocean, you’ll have access to 24/7/365 medical advisory services, field rescue from the point of injury, and medical evacuation to the nearest hospital or home hospital of choice. And even if you’re skiing at your local mountain, Global Rescue’s memberships now include local field rescue services within 100 miles of your home.