Flash Burn (Arc Eye): Symptoms, First Aid, and Prevention

Q: "What is arc eye or welder's flash?"

"Arc eye, also called welder's flash or flash burn, is essentially a sunburn of the cornea caused by intense ultraviolet light from a welding arc. The medical term is photokeratitis. The UV light damages the surface of the eye, and like a skin sunburn the pain shows up hours after the exposure, not during it. It is common among welders and bystanders who were not wearing adequate eye protection."

Q: "What are the symptoms of a flash burn?"

"Symptoms typically appear 3 to 12 hours after exposure and include a gritty, sandy feeling in the eyes, pain, redness, watering, sensitivity to light, and sometimes blurred vision. The delay is what catches people off guard, since they felt fine right after welding. Both eyes are usually affected. Most cases heal on their own within a day or two as the eye surface regenerates."

Q: "When should you see a doctor for arc eye?"

"Seek medical care if the pain is severe, if vision is significantly affected, if symptoms do not improve within a day or two, if there is any chance something is embedded in the eye, or if you are unsure. A doctor can confirm the diagnosis, rule out a foreign body or more serious injury, and provide treatment to manage pain and prevent infection. This is general safety information, not medical advice, so when in doubt get it checked."

Published June 9, 2026 · Updated June 9, 2026 · 4 min read

Flash burn has a cruel feature that sets it apart from most welding injuries: you do not feel it happen. You weld or watch someone weld without proper eye protection, finish the job feeling completely fine, and then hours later, often in the middle of the night, your eyes feel like they are full of sand and you cannot stand the light. That is arc eye, and while it is usually temporary and heals on its own, it is painful, preventable, and a warning that your eyes took real damage. This page is general safety information, not medical advice.

What Arc Eye Actually Is

A welding arc throws off intense ultraviolet light, the same kind of radiation that burns your skin at the beach. Arc eye, also called welder’s flash or flash burn, is a sunburn of the eye. The UV light damages the surface of the cornea, the clear front layer of the eye, in a condition doctors call photokeratitis. Just as a skin sunburn is not painful while you are getting it, the eye damage is silent at the time. The pain comes later as the injured surface cells react.

This is why arc eye catches so many people, including bystanders who just glanced at someone else’s arc or stood nearby without protection. You do not need to be the one welding, and you do not need a long exposure. A few unprotected looks at a bright arc can do it. The connection to UV is also why our eye protection guide stresses correct lens shade so heavily.

Recognizing the Symptoms

The hallmark of arc eye is the delay. Symptoms usually show up several hours after exposure, commonly in the range of three to twelve hours, which is what makes the cause confusing if you do not know to expect it. You felt fine after welding, so the burning eyes at bedtime seem to come from nowhere.

The symptoms themselves are distinctive: a gritty, sandy sensation as if something is in your eyes, pain that can range from uncomfortable to severe, redness, watering, strong sensitivity to light, and sometimes blurred vision. Both eyes are usually affected, since both were exposed. The feeling that there is grit in your eye is so characteristic that it is one of the clearest signs the cause was UV exposure rather than an actual particle.

Basic First Aid

For a typical mild flash burn, the eye heals itself within a day or two as the damaged surface cells regenerate, and the first aid is about comfort and protection while that happens. Get out of bright light, since light sensitivity is part of the condition. Rest your eyes and avoid rubbing them, because rubbing irritated, sunburned eyes makes the damage worse. A cool, clean compress laid over closed eyes can ease the discomfort. Remove contact lenses and leave them out until your eyes have fully recovered. Over-the-counter pain relief can help with the ache.

What you should not do is ignore the possibility of something more serious. Flash burn first aid assumes the problem really is just UV exposure. If there is any chance a particle, a bit of grinding debris, or a piece of slag is actually in the eye, that is a different injury that needs proper attention, not home comfort measures.

When to Get Medical Help

Most flash burns resolve on their own, but some situations call for a doctor. Seek medical care if the pain is severe, if your vision is meaningfully affected or not clearing, if symptoms have not improved within a day or two, if you suspect a foreign body in the eye, or simply if you are unsure how bad it is. A clinician can confirm it is photokeratitis and not something worse, check for an embedded particle or a corneal scratch, and provide treatment to control pain and head off infection. Repeated flash burns over a career may also carry longer-term risks to the eyes, another reason to take prevention seriously rather than treating arc eye as a routine nuisance.

Prevention Is the Whole Point

Arc eye is almost entirely preventable, and prevention is far better than any first aid. Always wear a welding helmet with the correct lens shade for the process and amperage you are running, as laid out in our helmet shade guide. Wear safety glasses underneath the helmet so your eyes are protected even when the helmet is up. Use welding screens or curtains to shield bystanders and coworkers from your arc, since they are just as vulnerable as you are and often have no protection at all. And never look at a welding arc, even briefly, without proper eye protection, no matter whose arc it is.

A welding arc is brighter than it looks and its UV reaches farther than people expect. Treat every arc in the shop as something to shield your eyes from, protect the people around you as well as yourself, and arc eye becomes a problem you read about rather than one you wake up at 2 a.m. with.

Frequently Asked Questions

What is arc eye or welder's flash?

Arc eye, also called welder's flash or flash burn, is essentially a sunburn of the cornea caused by intense ultraviolet light from a welding arc. The medical term is photokeratitis. The UV light damages the surface of the eye, and like a skin sunburn the pain shows up hours after the exposure, not during it. It is common among welders and bystanders who were not wearing adequate eye protection.

What are the symptoms of a flash burn?

Symptoms typically appear 3 to 12 hours after exposure and include a gritty, sandy feeling in the eyes, pain, redness, watering, sensitivity to light, and sometimes blurred vision. The delay is what catches people off guard, since they felt fine right after welding. Both eyes are usually affected. Most cases heal on their own within a day or two as the eye surface regenerates.

When should you see a doctor for arc eye?

Seek medical care if the pain is severe, if vision is significantly affected, if symptoms do not improve within a day or two, if there is any chance something is embedded in the eye, or if you are unsure. A doctor can confirm the diagnosis, rule out a foreign body or more serious injury, and provide treatment to manage pain and prevent infection. This is general safety information, not medical advice, so when in doubt get it checked.