Photokeratitis: Snow Blindness, Welder's Flash, and Acute UV Burns to the Eye

Photokeratitis is an acute, painful inflammation of the cornea caused by exposure of inadequately protected eyes to ultraviolet radiation, essentially a sunburn of the eye's surface. It goes by several names depending on the source: **snow blindness** (UV reflected off snow), **arc eye** or **welder's flash** (from welding arcs), and **corneal flash burn**. The damage is concentrated in the corneal epithelium, the outermost cell layer, which strongly absorbs UVB. Typical triggers include welding without eye protection, tanning beds used without goggles, and reflected sunlight. Reflective surfaces are the classic outdoor cause: fresh snow reflects about 80% of incident UV, sea foam around 25%, and sand around 15%, which is why mountaineers, skiers, and people on the water are especially at risk. UV intensity also climbs roughly 4% for every 300 meters of altitude, compounding the risk at high elevation. **Symptoms** are delayed, usually appearing 6 to 12 hours after exposure: intense pain, a gritty foreign-body sensation, heavy tearing, eyelid twitching, severe light sensitivity, and sometimes temporary vision blurring. The delay between exposure and pain is a hallmark that distinguishes it from immediate mechanical injury. **Recovery** is usually rapid and complete: healing typically takes 24 to 72 hours once the UV source is removed, because the corneal epithelium regenerates quickly. Management is supportive, removing the source, applying cool compresses, using artificial tears, and pain control with NSAID eye drops or systemic analgesics. Unlike the cumulative damage behind Pterygium (Surfer's Eye): A UV-Driven Growth on the Surface of the Eye and UV-Related Cataract: How Sunlight Clouds the Lens of the Eye, a single bout of photokeratitis rarely leaves permanent harm, though repeated episodes contribute to long-term surface damage. Prevention is simple: UV400 sunglasses, snow goggles, or proper welding filters. The Inuit and Yupik historically carved slitted snow goggles for exactly this purpose. See UV Eye Damage: Why Sunglasses Are Medical Equipment, Not Just an Accessory for the broader picture. *General informational content, not medical advice.*