What is UV Keratitis (Ultraviolet Injuries to the Eye)
UV keratitis, also known as snow blindness, is a photochemical injury to the cornea caused by acute high-dose ultraviolet radiation exposure that presents with ocular pain, tearing, conjunctival chemosis, blepharospasm, and vision deterioration typically several hours after exposure, lasting up to 3 days 1.
Clinical Presentation and Mechanism
UV keratitis results from the toxic effects of high-dose UV radiation on the ocular surface, representing a photochemical injury rather than a thermal burn 2. The condition characteristically has a delayed onset of symptoms occurring several hours after UV exposure, which distinguishes it from immediate traumatic injuries 1.
Key Clinical Features:
- Ocular pain (often severe)
- Excessive tearing (lacrimation)
- Conjunctival chemosis (swelling)
- Blepharospasm (involuntary eyelid closure)
- Deterioration of vision
- Symptom duration: up to 3 days 1, 2
High-Risk Populations and Environments
Mountaineers, skiers, and beachgoers are at particularly high risk due to extremely high UV reflectivity in these environments 1, 2. The reflectivity of UV radiation from snow, water, and sand dramatically increases exposure intensity beyond direct sunlight alone 3.
Environmental Risk Factors:
- Snow and ice (highest reflectivity)
- Water surfaces
- Sand
- Higher altitudes (increased UV intensity)
- Midday sun exposure (10 a.m.–4 p.m., peak UV-B radiation) 3
Related UV Eye Injuries
Beyond UV keratitis, solar retinopathy can occur from unprotected sun gazing, particularly during eclipse tourism or at higher altitudes, resulting in acute foveal injury and outer retinal defects 1. Additionally, artificial UV radiation from sunlamps and tanning beds has been linked to ocular melanoma 3.
Prevention Strategies
Using appropriate eye protection is crucial and represents the primary prevention strategy 1. The most recent guidelines emphasize:
Recommended Eye Protection:
- Sunglasses blocking 99% of UV-A and UV-B radiation (American Academy of Ophthalmology recommendation) 3
- Specialized solar filters or eclipse glasses (certified and meeting safety standards)
- Goggles with polarized or photochromic lenses
- Sunglasses with sidepieces for lateral protection 1
Important Caveat:
Protection does not correlate with lens color or darkness—the protective mechanism is a chemical coating applied to the lens surface 3. Dark lenses without UV coating can actually be more dangerous as they cause pupil dilation, allowing more UV radiation to enter the eye.
Combined Protection:
Sunglasses reduce UV radiation exposure to the eye by 80%, and when combined with a wide-brimmed hat (>3-inch brim), UV exposure to the face is reduced by 65% 3.
When to Seek Medical Attention
Based on the 2024 American Heart Association and American Red Cross First Aid Guidelines 4:
Seek immediate medical attention if:
- Persistent foreign-body sensation in the eye
- High-velocity eye injury
- Penetrating eye injury
- Irregular pupil after trauma
- Eye bleeding after trauma
- Loss of vision after trauma
Do not rub the eye if experiencing foreign-body sensation, as this can worsen corneal injury 4.
Clinical Management Considerations
While the evidence provided focuses primarily on prevention, the natural history indicates that UV keratitis is self-limited, typically resolving within 3 days 1, 2. The delayed onset of symptoms (several hours post-exposure) is a key diagnostic feature that helps distinguish UV keratitis from other acute ocular injuries.
The pathophysiology involves photochemical damage to corneal epithelial cells from UV radiation, particularly UV-B, which is most intense during midday hours and increases with altitude and reflective surfaces 3, 2.