Dr. Will Duffin – Joint Medical Director & GP
Will is a jobbing Devon based GP, educator and adventure addict. He has provided medical cover for dozens of very different expeditions and projects; including commercial high-altitude treks in The Himalayas and The Andes, a luxury Trans-Siberian private train, a reality TV show in the South Pacific and he has worked with UNICEF out in forgotten corners of Myanmar.
Anyone who’s spent time in the polar regions, at high altitude, or on the ocean can attest to the dazzling power of the sun’s rays. Snow, ice, and water are all very effective at reflecting light back up at us, and at higher elevations the thinner atmosphere means more UV light penetrates through. This can lead to fried eyes, otherwise known as ‘photokeratitis’ or ‘snow blindness’.
Mawson’s Antarctic Tragedy
Curiously, sunglasses weren’t in common use until the 1920’s. Up until this point early polar explorers relied on Inuit snow goggles – those rudimentary blocks of woods or ivory with horizontal slits for eye holes (Ref 1). Many expeditioners succumbed during the ‘Heroic Age’ of Antarctic exploration. One of the most fabled examples is Douglas Mawson’s ill-fated expedition to the South Pole by Dogsled in 1912. To compound a series of disasters, all three members of Mawson’s party developed snow blindness, the excruciating pain of which couldn’t be relieved by the preferred treatment at the time – cocaine. This undoubtedly contributed to Lieutenant Ninnis falling into a crevasse along with their remaining supplies and best dogs. Only Mawson survived the ordeal. (Ref 2)
Preventing Snow Blindness Today
Tales like these often celebrate the ‘indomitable spirit’ of explorers of the time, how they struggled on regardless in their hobnail boots and woolly jumpers. Fortunately, snow blindness is now very much a preventable problem thanks to modern equipment in the form of eye protection: glasses or goggles with a minimum of category 4 lenses, letting in less than 8% of UV light. (Cat 3 lenses and below aren’t going to cut it!)
The right equipment only works, however, when it’s used properly. Part of the role of the Medic in such extreme environments is keeping tabs on whether other expedition team members are protecting themselves properly. Nowadays snow blindness is more likely to be encountered when an expedition member forgets to wear their goggles, classically when ambient light levels are lower during low cloud or fog. Be wary, this is a trick! The invisible UVB rays have a shorter wavelength than visible light and still penetrate through. It’s essential for everyone to remain compliant even on the most overcast days. Top tip: always carry spare sunglasses or goggles for the unfortunate soul who left their only pair next to their wee patch in the snow.
Recognising Snow Blindness Symptoms
The symptoms of snow blindness to look out for include burning eye pain, redness and irritation, sensitivity to light (photophobia) excessive tearing (epiphora), and ultimately blurred vision and reduced visual acuity. There is usually a delayed onset of symptoms of between 6-12 hours after intense UV exposure. Unlike infective conjunctivitis, snow blindness is almost always bilateral. Be extra cautious with contact lens wearers who are at much higher risk of a range of eye problems and complications.
Managing Snow Blindness
Whilst mild to moderate cases will heal spontaneously, a well-stocked med bag with a range of different eye drops will definitely come in handy if you’re the expedition medic. Management options include artificial tears (something like Hylo Forte) and topical anaesthetic drops (such as Amethocaine) for immediate pain relief to assist with examining the eyes. A topical NSAID (such as Ketorolac) is useful alongside oral paracetamol and weak opioids (such as Oxycodone or Co-codamol) for more medium-term analgesia. Consider also a topical cycloplegic (such as Cyclopentolate) which can reduce spasms of the ciliary muscles that contribute to pain. Another option is placing temporary patches on the eyes. If you do this remember to remove at regular intervals to apply medication and to reassess. Don’t apply topical steroid drops (such as Pred Forte). These are contraindicated due to concerns they can delay healing. Severe cases can be truly incapacitating, and evacuation/descent will require high levels of assistance if done on foot. (Ref 3)
And finally for one of nature’s most amazing secrets: Polar bears don’t wear sunnies, so why don’t they get snow blindness? This will blow your mind… they have THREE eyelids and corneas rich in Vitamin C that absorb UV rays. What clever creatures.
- Antarctic heritage trust https://nzaht.org/snowblindness/
- The Most Terrible Polar Exploration Ever: Douglas Maswon’s Antarctic Journey. Smithosnian Magazine. https://www.smithsonianmag.com/history/the-most-terrible-polar-exploration-ever-douglas-mawsons-antarctic-journey-82192685/#:~:text=For%20the%20first%20few%20days,pair%20had%20to%20slow%20down.
- Field Guide to Wilderness medicine Fifth Edition. Paul S auerbach. 2019. Elsevier pp388-389.
- Polar bears International https://polarbearsinternational.org/news-media/articles/how-polar-bears-avoid-snow-blindness
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