Welding is a manufacturing process that uses high heat to melt and fuse materials. Arc welding generates an electric arc that creates temperatures reaching thousands of degrees Celsius. This intense energy produces extremely bright light and a broad spectrum of invisible electromagnetic radiation dangerous to human tissue, particularly the eyes. This energy output necessitates specialized protection when viewing the arc.
The Invisible Threat: Understanding Welding Radiation
Arc welding generates emissions across the electromagnetic spectrum, including ultraviolet (UV) radiation, visible light, and infrared (IR) radiation. The most damaging components are high-energy UV rays (UV-C and UV-B), which are produced directly by the arc and are normally filtered by Earth’s atmosphere. Visible light causes immediate discomfort and can lead to temporary blindness, but UV radiation is the primary source of biological damage. IR radiation, perceived as heat, contributes to eye injury by heating internal structures, making the combination of these radiations a threat to unprotected vision.
The Biological Impact: The Mechanism of Eye Damage
The radiation from a welding arc causes an injury known as photokeratitis, commonly called arc eye or welder’s flash. This condition is essentially a sunburn on the cornea, the transparent outer layer at the front of the eye. When exposed to UV light, the energy is absorbed primarily by the corneal epithelium, the outermost layer of cells. This absorption damages the cellular structure, leading to the death of these epithelial cells.
Damage accumulates rapidly during exposure, but symptoms are often delayed. The exposed epithelial cells begin to break down, causing noticeable discomfort and pain 6 to 12 hours later. This delay occurs because the nerve endings beneath the epithelial layer are not exposed until the damaged surface cells slough off. Photokeratitis is a surface-level, radiation-induced burn, not an injury to the inner eye.
Immediate Symptoms and Recovery
Once damaged corneal cells shed, the exposed nerve endings trigger painful symptoms. Common complaints include a foreign body sensation, caused by the roughness of the damaged corneal surface. Sharp pain, involuntary tearing (lacrimation), and extreme sensitivity to light (photophobia) are characteristic of photokeratitis. The damage can also temporarily blur vision due to the irregularity of the corneal surface.
The corneal epithelium has a capacity for regeneration in most cases of arc eye. Recovery is rapid, often resolving completely within 24 to 48 hours as healthy surrounding cells migrate to cover the surface. Treatment focuses on managing pain and discomfort, often involving cold compresses, lubricating eye drops, and oral pain relievers. While the condition is temporary, any instance of exposure should be evaluated by a healthcare professional to rule out secondary infections or severe damage. Approved protective eyewear is necessary to prevent this condition entirely.