What you should know about Photokeratitis – Sun Damage and Snow Blindness Explained
Photokeratitis, also known as ultraviolet keratitis, is a painful but temporary affliction of the eye that develops after exposure to UV rays. Symptoms include severe eye pain, light sensitivity (photophobia) and excess tears. Symptoms can last up to 48 hours, with longer exposure to UV leading to more severe symptoms.
Rarely, changes to vision including temporary changes in colour can occur. If you notice changes in your or your child’s vision, it is best to get checked by an eye care professional.
What causes photokeratitis?
The cornea is the clear outer surface at the front of the eye, which helps us focus light to see clearly.
Like our skin, the cornea can be burned by sunlight or UV rays. In fact, photokeratitis is often compared to a sunburn of the eye. This is because the cornea- in particular the corneal epithelial cells- are damaged by UV rays and, after a few hours, begin to slough off. The result leaves the corneal nerves underneath exposed and damaged.
Sources of Exposure
As kids, we all hear it at some point or another: “never stare into the sun!” While this advice may seem like common knowledge, harmful UV light can also come from various synthetic sources and can negatively affect the eyes.
The most common examples are found in arc welders and snow blindness from the sun’s reflections.
Many other sources of UV can cause photokeratitis however:
- Arc welding (arc eye or welder’s eye)
- Snow reflecting sunlight into the eyes (snow blindness)
- UV lamps or germicidal lamps
- Sun lamps
- Tanning beds
- Broken mercury vapour lamps or halogen lamps
- Staring at the sun without protection
Snow blindness is more likely at higher altitudes, as UV rays are more intense the higher up we go. Another risk factor is freshly fallen snow, which reflects more light. However, snow blindness does not require snow, and can occur due UV light with many light colored or reflective surfaces nearby like water, sand, concrete, and ice.
How is photokeratitis diagnosed?
An eye doctor will typically ask for a history of past activities.
A physical examination of the eye commonly shows both eyes being affected, rather than a single eye.
Optometrist can also use an orange dye called fluorescein, in the form of eye drops, to inspect the eye and see UV damage to the cornea. The dye will show areas of staining on the corneal epithelium, which are areas that were damaged and sloughed off.
How is photokeratitis treated?
Fortunately, photokeratitis is a temporary condition and the corneal epithelium generally heals within 1-3 days.
Supportive treatments such as artificial tears, topical antibiotic ointments, and oral painkillers are used to treat symptoms until the cornea heals.
Photokeratitis is preventable. Patients can wear sunglasses with UV blocking properties, and occupational hazards such as welding can be avoided by following health and safety protocols and wearing a welding mask.
After diagnosis, a follow-up appointment with an eye doctor should be made within two days. If symptoms worsen or new symptoms appear, a re-evaluation may be necessary.
Read more about Photokeratitis from the College of Optometrists: https://www.college-optometrists.org/guidance/clinical-management-guidelines/photokeratitis-.html
Read more about UV radiation and occupational safety from the Canadian Center for Occupational Health and Safety (CCOHS): https://www.ccohs.ca/oshanswers/phys_agents/ultravioletradiation.html