Snow blindness can sneak up on you, but prevention is easy

As the only American to have climbed all 14 of the world’s peaks over 26,000 feet above sea level — and the fifth person to do so without using supplemental oxygen — high-altitude mountaineer Ed Viesturs has come closer to the sun here on Earth than most of us ever will.

Among the things the 61-year-old always brings on big adventures is an essential accessory for anyone spending time outdoors this winter: protective eyewear.

“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 Viesturs, referring to the medical condition known as photokeratitis.

A temporary but painful condition, it occurs when exposure to ultraviolet rays creates inflammation on the surface of the eye.

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

While he has not suffered the condition himself, Viesturs has helped many others reeling in pain from it during expeditions. “The best description I’ve heard is that it feels like someone is pouring sand in your eyes,” he said.

Even if you’re more focused on snowshoeing or simple hikes than bagging big peaks this winter, snow blindness is something that can creep up on you in much milder conditions — and much closer to sea level — too.

Protective eyewear is your best defense

The easiest way to think of photokeratitis, said Dr. Brian Zaugg, a cornea specialist with the John A. Moran Eye Center at the University of Utah in Salt Lake City, is like getting a sunburn on your eyes.

“People don’t realize their eyes are covered in skin like the rest of their body,” he said. “So they’re just as prone to getting a sunburn.”

“Most people, in the winter, they don’t cover their eyes,” he said. “They cover their whole body because it’s cold, and they leave their eyes uncovered. So they’re susceptible.”

Often painful, the condition can be accompanied with blurry vision and watery eyes, among other symptoms, and affects the eyes’ corneas and conjunctiva (the latter is the clear tissue over the white of your eye).

“Those are the parts that get the burn,” Zaugg said.

Despite its moniker, snow blindness doesn’t only occur in snowy and icy conditions.

“It happens at the beach as much as on snow,” he said. “The UV rays reflecting off snow and ice can create a double exposure (from sunlight overhead and the reflection on a surface) and that’s when it’s risky — it’s the same effect as staring at water.”

Ultraviolet radiation levels increase by 10% to 12% with every 1,000-meter increase in altitude, according to the World Health Organization.

Exposure at higher altitudes is more damaging since the air is thinner, making the UV exposure more intense, Zaugg said, but photokeratitis can happen at lower altitudes, too.

Despite the name, it can even be caused by the glare off pavement and sand.

“We think of higher elevations causing more problems,” Zaugg said. People used to living at sea level who take a ski trip to higher elevations, however, can be more prone to getting photokeratitis because they may not think to wear eye protection.

The good news is that a little eye protection goes a long way — and you hardly need to spend hundreds of dollars on sunglasses.

Indigenous cultures from the Arctic, including the Inuit and Inupiat, carved snow goggles from things like whale baleen and caribou bone, with narrow slits to peer through to reduce exposure to glare from snow and ice.

Regular sunglasses that block ultraviolet A and ultraviolet B rays do a good job of protecting against photokeratitis, Zaugg said. Wraparound sunglasses or ski goggles, he said, are better in conditions with motion (when you’re skiing, for example) that can bring on excess UV light through the peripheral angles.

A condition with a sneaky side

One of the tricky things about snow blindness is that it can sneak up on you, said Dave Keaveny, 41, a medical operations specialist for US-based integrated travel risk and crisis response provider Global Rescue.

Through his work with the organization, he has helped evacuate people suffering from photokeratitis during expeditions in the Himalayas and Mount Everest.

“The pain usually comes on after the exposure,” said Keaveny, who is also a professional ski patroller in New Hampshire, where he has seen increased outdoor recreation during the pandemic.

“Even on a cloudy day, you still have UV light that’s getting through the clouds and reflecting off the snow and can hurt your eyes,” he said. “It’s the same as getting a sunburn on the beach on an overcast day. The light may not be as intense, but it can still do damage.”

During expeditions that are inherently dangerous already, Keaveny said, “the distracting pain can lead to other injuries, so field rescue becomes the most important thing to do.”

“It’s kind of one of those things you might not know is happening until it’s too late,” said Viesturs, who always carries anesthetic eyedrops in his kit to treat snow blindness on the spot in case it occurs.

“If you’re trying to get someone off a mountain or down somewhere at least you can provide some relief,” added Viesturs, who is a member of Global Rescue’s Mountain Advisory Council.

How to self soothe

A mild case of photokeratitis might leave you with eyes that just feel tired at the end of the day, Zaugg said. But if you find your eyes burning after exposure to bright sunlight, there are a few things you can do.

“In the moment, you’re really just treating symptoms,” he said, which mostly means trying to lubricate the eyes with artificial tears.

“Most people can find comfort doing similar things you’d do with a sunburn,” Zaugg said.

Cool your eyes with cold artificial tears or a cold washcloth placed over your closed eyes, he said. “Anti-inflammatories like ibuprofen or Tylenol can help with the discomfort.”

In severe cases, however, the eyes can feel gritty.

“You can have the skin (on your eyes) so irritated where it’s essentially like an abrasion,” he said. In those situations, antibiotics may be prescribed to prevent an infection, or even topical steroids, he said.

“The nice thing about photokeratitis is it typically heals itself and doesn’t cause long-term permanent damage,” Zaugg said. “It usually takes about a week to feel significantly better.” If irritation doesn’t abate past a week, be sure to schedule an examination with your eye doctor.