Welding Flash and Sun Gazing Eye Burn: Arc Eye Pain Explained

Arc eye is a sunburn of the clear front window of the eye, caused by ultraviolet light from welding, and it shows up 6 to 12 hours later as sand-in-the-eye pain, streaming tears and light that hurts. It usually heals in a day or two with an eye doctor’s care. Staring at the sun is different: it burns the retina at the back, often painlessly, and can leave a permanent blind spot.

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Three in the morning. A young man from a gate-and-grille workshop wakes up shouting. He can’t open them. Tears pour. Sand in both eyes, he says, though there’s none, and when the family finally gets the story out of him it turns out he welded a few joints that afternoon without the mask because “it was only two minutes”. That delay, often six hours or more between the flash and the pain, is exactly what confuses people and sends them to the wrong place, because nothing hurt at the time and nobody links a quiet afternoon at the workshop with a night of agony. Classic.

Why arc eye hurts hours later

Welding arcs give off strong ultraviolet (UV) light, and the cornea, the clear dome at the front of the eye, soaks it up the way skin soaks up sun on a beach, so the top layer of cells is damaged but doesn’t die straight away. Think sunburn. Delayed. Then they peel. Hence the grit.

Did you know? It isn’t only welders. The same thing happens on snowy mountains and at sea, where UV bounces back up at the eyes. Climbers call it snow blindness.

Typical arc eye symptoms

• Gritty, burning pain in both eyes, starting 6 to 12 hours after exposure (often at night).
• Heavy watering and red eyes, swollen lids, twitching lids that clamp shut.
• Light sensitivity and blurred vision from the tears.
• Usually settles within 24 to 48 hours as the surface regrows.

What to do for welding flash eye pain

1. Take out contact lenses if you wear them.
2. Sit in a dim room. Cool, clean cloths over the closed lids for 10 minutes at a time can soothe, and keeping the lights low and the curtains drawn makes the light sensitivity far easier to bear while you wait to be seen.
3. Don’t rub. Rubbing peels more cells.
4. See an eye doctor or emergency department the same day. They’ll stain the cornea with a yellow dye and look under blue light to confirm it and rule out a metal fragment.
5. Follow the doctor’s plan: usually lubricating drops or ointment, sometimes an antibiotic ointment, and pain relief chosen for you. Don’t add or stop anything they prescribe on your own.
6. Rest.

Why no numbing drops at home

The doctor may use one anaesthetic drop to examine you, and the relief is dramatic. People ask to take the bottle home. No. Repeated numbing drops slow the healing of the cornea, and a numb eye can’t warn you when something else is wrong. Used over days, they can cause lasting damage and ulcers. Same for “whitening” drops.

Welding shield rules that prevent it

Arc eye is almost always preventable, and in practice the workshop habits around the mask, who wears it, when and for how long, matter far more than how much the mask cost. Habits win.

• Every strike, every time: a welding helmet or hand shield with the correct filter shade, even for a quick tack weld.
• The right shade: arc welding usually needs a dark filter, around shade 10 or darker. The helmet label and your welding process decide the exact shade; gas welding and cutting use lighter shades.
• Auto-darkening helmets: check the battery and sensor before work.
• Helpers and passers-by: the flash reaches anyone nearby. Use screens or curtains around the bay and keep children away. Often it’s the helper.
• Sunglasses aren’t welding filters. Nor are dark glass bottles or X-ray films.
• Grinding: wear impact-rated safety glasses under the helmet.

Sun gazing, eclipses and the retina

Sun gazing is promoted online as a morning ritual, and eclipses tempt everyone to look. Staring at the sun focuses its light onto the macula, the tiny centre of the retina used for reading and faces, and burns it. No pain, though. Hours later the person notices a blurred or dark spot in the middle of their vision, or straight lines that bend.

There’s no treatment that reverses it. Some people recover partly over the following months while others keep the spot for life, which means the only real protection is not to stare in the first place. Prevention, then:

• Never look at the sun directly, with or without sunglasses, and never through a phone camera, binoculars or telescope without a proper solar filter.
• For an eclipse, use eclipse glasses marked ISO 12312-2 that are undamaged, or watch through a pinhole projector with your back to the sun.
• Smoked glass, X-ray film and stacked sunglasses fail.
• Supervise children closely during an eclipse. They’ll peek. Always.

If vision is blurry after looking at the sun, cover each eye and look at a straight door frame. Wavy lines or a grey spot mean an eye doctor the same day, so the damage can be recorded and other causes ruled out. For simple dryness and grit without a burn, see our guide to dry gritty eyes, and the wider Eye Care section.

Arc eye and sun damage: common questions