A flash burn is the common term for the medical condition known as photokeratitis, which is essentially a painful sunburn on the eye. This temporary condition involves the inflammation of the cornea, which is the clear, dome-shaped tissue covering the iris and pupil at the front of the eye. It is caused by unprotected exposure to intense, invisible ultraviolet (UV) light. The damage affects the surface layer of the eye, similar to how sunburn affects skin.
How Ultraviolet Light Damages the Cornea
The eye’s structure is designed to absorb UV radiation to protect the deeper, more sensitive internal components. The cornea, specifically its outermost layer, the epithelium, absorbs the vast majority of incoming UV-B and UV-C rays. This absorption is what causes the damage, essentially sacrificing the epithelial cells to shield the inner eye from harm.
When the cornea is exposed to an excessive dose of UV energy, the delicate epithelial cells are damaged and begin to break down or slough off. This leaves the underlying corneal nerve endings exposed and unprotected, which is the direct cause of the severe pain experienced by the patient. The damaging radiation can come from many surprising sources, not just the sun.
The most common source of intense UV exposure is a welding arc, which is why the condition is frequently called “arc eye” or “welder’s flash”. Other causes include prolonged use of sunlamps or tanning beds without proper eye protection. Even natural phenomena like sun glare reflecting off snow or water can cause this injury, a form known as “snow blindness,” particularly at high altitudes where the atmosphere offers less filtering.
Identifying the Signs of Injury
Symptoms begin to develop six to twelve hours after the initial exposure to the intense light source. This delayed onset can make it difficult for a person to immediately connect the pain to the exposure event. A person may be fine while welding or skiing, only to wake up in the middle of the night with significant pain.
The most noticeable signs include:
- Sudden, severe, and persistent pain in both eyes.
- A foreign body sensation, often described as feeling like sand or grit trapped beneath the eyelids.
- Excessive tearing (lacrimation) and noticeable redness.
- Extreme sensitivity to light (photophobia), causing discomfort in even dimly lit environments.
- Eyelid twitching and blurred vision.
The intensity of symptoms correlates with the duration and strength of the initial UV exposure. Prompt medical attention is often sought due to the acute pain.
Essential First Aid and Professional Treatment
Immediate action following a suspected flash burn should focus on minimizing discomfort and preventing further injury. The most important first step is to move immediately into a dark room or shaded area to reduce light exposure. Applying a cool compress or washcloth over the closed eyes can help soothe the inflammation and reduce swelling.
It is imperative not to rub the eyes, as this can worsen the damage to the already compromised corneal surface. If contact lenses are being worn, they must be removed immediately. Over-the-counter pain relievers, such as ibuprofen, may be taken to manage the discomfort until professional medical help is obtained.
A medical professional, such as an ophthalmologist, will confirm the diagnosis by applying a special orange dye called fluorescein to the eye surface. When viewed under a cobalt blue light, the dye highlights the damaged areas of the corneal epithelium, revealing the extent of the burn. Prescription treatment includes lubricating drops or artificial tears to keep the eye moist and comfortable while it heals.
The doctor may prescribe topical antibiotic drops or ointment to prevent secondary bacterial infection. For severe pain, a temporary eye patch may be applied to immobilize the eyelid and promote healing, though this practice is less common. Topical anesthetic drops are never prescribed for home use, as they mask pain and can impede the healing process.
The Rapid Healing Process
Despite the intense pain, photokeratitis is a temporary condition with an excellent prognosis, and permanent vision loss is extremely rare. The corneal epithelium has a remarkable capacity for regeneration, which facilitates rapid healing. Most symptoms begin to subside significantly within 24 to 48 hours after the injury and proper treatment begins.
The full recovery, including the complete restoration of the corneal surface, occurs within one to two days. Any lingering discomfort or blurred vision is resolved within this period. Long-term problems only arise from chronic, repeated exposure to UV light or if a secondary infection develops and is left untreated.
Prevention involves wearing proper protective eyewear whenever exposure to intense UV radiation is a risk. This means using UV-blocking safety goggles or a helmet with the correct filter shade when welding. When outdoors in bright conditions, especially near snow, water, or sand, wearing sunglasses that block 99% to 100% of UV rays is a highly effective preventative measure.