Arc eye, also known as welders flash or photokeratitis, is a painful inflammation of the cornea caused by intense exposure to ultraviolet (UV) radiation. This condition is a radiation burn to the outer layer of the eye, similar to a sunburn. The damage occurs when the cornea absorbs high levels of UV light emitted from a welding arc, injuring the delicate layer of cells on the eye’s surface.
The Mechanism of Injury and Exposure Time
The amount of time required to cause arc eye is short, as damage depends on the intensity of the UV light delivered, not prolonged exposure. Unprotected viewing of a welding arc can cause a corneal burn in just a few seconds; a single split-second flash is enough to begin the injury process. The electric arc produces highly energetic UVC and UVB wavelengths, which are almost entirely absorbed by the cornea.
This intense absorption damages the epithelial cells on the cornea’s surface, causing them to slough off and expose underlying nerve endings. Factors like the distance from the arc and the specific welding process affect the total intensity of radiation delivered. There is no safe minimum exposure time without the correct protective equipment.
Recognizing the Damage
A deceptive characteristic of arc eye is the latency period—a delay between exposure and the onset of severe symptoms. Symptoms typically begin six to twelve hours after the incident, often leading the exposed individual to believe they have escaped injury. When the pain arrives, it ranges from a severe, burning sensation to the feeling of having foreign objects, like sand, trapped in the eyes.
Affected individuals usually experience photophobia, an extreme sensitivity to light. Other common indicators include excessive tearing, red and bloodshot eyes, and temporary blurred vision. The pain can cause eyelid muscle spasms, making it difficult to keep the eyes open.
Immediate Care and Recovery
Upon recognizing symptoms, the first step is to move to a dark environment and apply a clean, cool compress over the closed eyes to soothe discomfort. Avoid rubbing the eyes, as this worsens damage to the compromised corneal surface. Any contact lenses should be removed and not reinserted until irritation has fully resolved. Seeking professional medical attention is necessary for proper diagnosis and pain management.
Medical Treatment
Medical treatment often includes antibiotic eye drops or ointment for a few days to prevent a secondary bacterial infection. Pain relief is managed with over-the-counter medication like paracetamol or ibuprofen. Lubricating eye drops may also be recommended to keep the eyes moist and comfortable. The corneal epithelium heals rapidly, and most cases of arc eye resolve completely within 24 to 48 hours. While permanent vision damage is rare, repeated or severe exposure can lead to long-term issues like scarring or chronic light sensitivity.
Essential Prevention Measures
Preventing arc eye relies entirely on using the correct personal protective equipment (PPE) that blocks harmful UV radiation. The most important equipment is a welding helmet fitted with a filtered lens that has an appropriate shade number. The shade number indicates the lens’s ability to filter light; for most arc welding processes, a shade between 10 and 14 is required.
Welders should select the shade based on the specific process and welding current, as higher amperage necessitates a darker filter. Automatic darkening filters (ADF) are highly recommended, as they automatically switch from a light state to a dark, protective shade within milliseconds of the arc igniting. Safety protocols must also protect bystanders, who should never look at an arc and must be shielded by welding screens or curtains.