Snow blindness is almost always temporary. The pain, blurred vision, and light sensitivity typically clear up on their own within 24 to 48 hours, and most people recover fully without any lasting damage to their eyes. That said, the condition is genuinely painful while it lasts, and repeated episodes over time can contribute to more serious eye problems.
What Snow Blindness Actually Is
Snow blindness is a sunburn on the surface of your eye. The medical term is photokeratitis: inflammation of the cornea caused by ultraviolet light. UV rays damage the thin layer of cells covering the cornea in the same way they burn exposed skin. The cornea absorbs most of the UV radiation that hits your eye, and when the dose is high enough, the surface cells are injured or killed.
At the cellular level, UV radiation damages DNA inside corneal cells and triggers a burst of harmful molecules called reactive oxygen species. This combination disrupts normal cell function and causes inflammation. But the corneal surface regenerates quickly. New epithelial cells replace the damaged ones within a day or two, which is why the condition resolves so fast compared to UV damage on skin.
Why Snow Is Especially Dangerous
Fresh snow reflects about 85% of UV radiation back upward toward your face. For comparison, grass and turf reflect only about 2.5%, dry sand reflects 17%, and calm water reflects roughly 5% (though that percentage climbs sharply at low angles). This means that on a bright day in the mountains, UV light is hitting your eyes from both above and below. Altitude compounds the problem: UV intensity increases about 10% for every 1,000 meters of elevation gain. Skiers, snowboarders, mountaineers, and even casual hikers on snowfields are all at risk.
Overcast skies don’t offer reliable protection. Clouds scatter UV light but still allow a significant percentage through, and the reflection off snow beneath you remains high regardless of cloud cover.
Symptoms and How Quickly They Appear
Like a sunburn on skin, snow blindness isn’t noticeable until well after the damage has already happened. There’s typically a delay of several hours between UV exposure and the onset of symptoms. You might spend a full day skiing without goggles and feel fine until that evening, when the pain starts.
Common symptoms include:
- Pain or burning in both eyes, often described as a gritty, sand-in-the-eyes sensation
- Tearing and redness
- Blurred vision
- Sensitivity to light
- Swollen eyelids
- Temporary vision loss in severe cases
Symptoms usually last 6 to 24 hours and disappear within 48 hours. During the worst of it, even dim indoor lighting can feel painfully bright.
Recovery and What Helps
The cornea heals itself without medical intervention in most cases. While you’re waiting it out, staying in a dim or dark room helps significantly with comfort. Removing contact lenses, if you wear them, reduces irritation against the damaged surface. Cool, damp compresses over closed eyes can ease the burning. Over-the-counter pain relievers help with the ache.
Rubbing your eyes is tempting but makes things worse by further irritating the damaged corneal surface. Artificial tears (preservative-free drops) can soothe the gritty feeling. If your symptoms haven’t improved noticeably after 48 hours, or if you experience severe vision changes, that warrants a visit to an eye care provider, since prolonged symptoms could indicate deeper corneal damage or a secondary infection.
When Repeated Episodes Become a Problem
A single episode of snow blindness heals cleanly. The concern is cumulative UV exposure over years. Each time the cornea is burned and repaired, the process introduces low-level cellular stress. Over many episodes, this repeated cycle of damage and regeneration can contribute to longer-term conditions. Chronic UV exposure to the eyes is a known risk factor for cataracts (clouding of the lens), pterygium (a fleshy growth on the white of the eye that can encroach on the cornea), and certain degenerative changes in the retina.
None of these happen from one bad day on the mountain. They develop from a pattern of unprotected UV exposure over years or decades. People who work outdoors in snowy or high-altitude environments, or who ski frequently without proper eye protection, accumulate the most risk.
How to Prevent It
Proper eyewear is the only reliable prevention. For snow sports, goggles are rated by how much visible light they let through, called VLT (Visible Light Transmission). Lower VLT means darker lenses that block more light. On bright, sunny days at high altitude or on glaciers, you want goggles in the 5 to 10% VLT range. Normal sunny or mixed-light conditions call for 10 to 20% VLT. Overcast days or skiing through trees are best matched with 20 to 40% VLT.
The VLT rating controls brightness and glare, but UV protection is a separate feature. Look for lenses labeled UV400, which block all UV wavelengths up to 400 nanometers, covering both UVA and UVB. Most quality ski goggles include full UV protection regardless of lens tint, but cheaper options may not.
Wrap-around sunglasses work well for hiking and mountaineering when goggles feel like overkill. The key is blocking light from entering around the edges of the frames. Standard flat-front sunglasses leave gaps at the sides and bottom where reflected UV from snow can reach your eyes. If you’re caught without any eyewear in an emergency, even a makeshift slit cut into cardboard, tape, or fabric and held over your eyes will reduce UV exposure substantially. This is the same principle behind traditional Inuit snow goggles, which were carved from bone or wood with narrow horizontal slits.