Welding involves fusing materials with intense heat, generating an extremely bright and powerful arc of light. This arc is a source of intense electromagnetic radiation, posing a significant hazard to the unprotected human eye. Eye injury is a serious risk associated with welding, affecting the person performing the work and unprotected bystanders. Understanding the nature of this damage is fundamental to ensuring safety.
Photokeratitis (Arc Eye) – The Acute Injury
The most common eye injury resulting from a single, short exposure to the welding arc is photokeratitis, often called arc eye or welder’s flash. This condition is essentially a severe sunburn of the cornea, the clear outer layer at the front of the eye. It is caused by exposure to the intense ultraviolet (UV) radiation emitted by the arc, and even a fleeting glance at an arc without proper protection can transmit enough UV energy to cause injury.
The timeline for this acute injury is characterized by a significant delay between the exposure and the onset of symptoms. While the exposure itself might last only seconds, the painful symptoms typically begin to manifest between 3 and 12 hours later. Symptoms include severe pain, a sensation of having sand or a foreign body in the eye, excessive tearing, and an abnormal sensitivity to light.
Fortunately, photokeratitis is nearly always a temporary condition that does not cause permanent blindness. Because the damage is limited to the superficial layer of the cornea, the tissue has a remarkable capacity to heal itself. Symptoms usually begin to resolve within 24 to 48 hours as the damaged cells are replaced by new ones. Although functional vision loss can be complete during the painful period, long-term vision is typically unaffected if the eyes are rested during healing.
Long-Term Risks and Permanent Vision Loss
While acute flash burns rarely cause lasting damage, repeated or cumulative exposure to welding radiation without adequate protection can lead to permanent vision degradation and loss. This chronic damage results from years of repeated, unprotected exposure to lower levels of radiation.
One significant long-term effect is the formation of cataracts, which involves the clouding of the eye’s lens. Cumulative UV exposure causes proteins in the lens to break down over time. Prolonged exposure to infrared (IR) radiation also contributes to cataract formation through a thermal effect on the lens tissue.
The intense light from the arc also poses a risk to the retina, the light-sensitive tissue at the back of the eye. While rare, a direct, unprotected exposure to the arc can cause a thermal burn on the retina in a fraction of a second. Repeated exposure to intense visible light, especially blue light wavelengths, can also contribute to the progressive deterioration of the retina, leading to long-term vision impairment.
Understanding the Role of UV and IR Radiation
The danger in the welding arc stems from the broad spectrum of electromagnetic radiation it produces, which includes UV, visible light, and IR radiation. Each type of radiation affects a different part of the eye, dictating the nature of the resulting injury.
The cornea absorbs the majority of UV-C and UV-B wavelengths, causing arc eye. The longer UV-A wavelengths are absorbed by the lens, contributing to opacification and cataracts over many years.
IR radiation is perceived as heat and penetrates deeper than UV, absorbed by the lens and retina. Its thermal effects contribute to the long-term development of cataracts. The intensely bright visible light component can temporarily overwhelm the eye’s natural defenses, causing dazzling and potential damage with chronic exposure.
Essential Safety Measures for Eye Protection
Preventing both the acute and chronic damage caused by welding radiation requires strict adherence to protective measures. The most important defense is the use of appropriate Personal Protective Equipment (PPE), specifically a welding helmet or shield. These devices are equipped with specialized filter lenses that block the harmful UV and IR radiation while reducing the intensity of visible light to a safe level.
Selecting the correct lens shade is necessary for maximizing protection. Filter lenses are rated with a shade number, and the required darkness depends on the welding type and amperage used. All welding eye protection must meet established safety standards, certifying their ability to withstand impact and filter the specified range of radiation.
Bystanders and nearby workers must also be protected, as the arc’s radiation can cause photokeratitis even from a distance. Safety glasses with side shields should be worn under the welding helmet to protect against flying debris and sparks. Consistent use of the correct, certified equipment prevents both short-term pain and cumulative vision loss.