Photokeratitis makes the eyes look noticeably red and watery, often with visible swelling around the eyelids. It’s essentially a sunburn on the surface of your eye, caused by overexposure to ultraviolet light, and the visible signs closely mirror what you’d expect from a burn: inflamed, irritated tissue that looks angry and wet. The condition is temporary, typically resolving within one to three days.
How Photokeratitis Looks From the Outside
The most obvious sign is redness. In a study of eight patients who developed photokeratitis after UV exposure at an outdoor event, 75% had visibly red eyes. This redness comes from dilated blood vessels around the cornea (the clear front surface of your eye), a pattern eye doctors call ciliary vasodilation. Unlike the patchy redness you might see with allergies, photokeratitis tends to produce a more uniform, deep redness concentrated around the colored part of the eye.
Tearing is the second hallmark. About 63% of patients in that same study had excessive tearing, giving the eyes a glassy, wet appearance. Combined with the redness, this often makes people assume they have pink eye. Swelling around the eyelids can also be visible, and in some cases the pupils appear noticeably smaller than usual. Eyelid twitching is another sign that others might notice.
What It Feels Like From the Inside
The visual symptoms only tell part of the story. What drives most people to search for answers is how it feels. The dominant sensation is pain, present in virtually every case. It’s often described as a gritty, sandpaper-like feeling, as though something is stuck in your eye that you can’t blink away. This foreign-body sensation comes from microscopic damage to the outermost layer of the cornea, where UV radiation kills surface cells and loosens the protective epithelial layer.
Light sensitivity is intense. Bright lights feel painful, and you may see halos around light sources. Blurry vision is common, though most people retain functional visual acuity. Headaches frequently accompany the eye symptoms. In rare cases, people experience temporary vision loss, though this resolves as the cornea heals.
Why Symptoms Don’t Appear Right Away
One of the trickiest things about photokeratitis is the delay. You won’t notice anything wrong while the UV exposure is happening. Symptoms typically develop 6 to 12 hours later, though they can take up to a full day to appear. This lag catches people off guard because by the time their eyes turn red and start hurting, they’re no longer in the sun, near a welding arc, or on the ski slope that caused the damage.
The delay happens because UV radiation triggers a cascade of cellular damage that takes hours to fully develop. The radiation causes cells across all layers of the cornea to undergo programmed cell death, a process that begins around five hours after exposure based on animal studies. Inflammatory signals build during this window, eventually sensitizing pain receptors and suppressing the eye’s normal cooling mechanisms. The result is that discomfort ramps up steadily over several hours before peaking.
What Doctors See Under Examination
If you visit an eye doctor, they’ll likely use a yellow-green dye called fluorescein that glows under blue light to reveal corneal damage invisible to the naked eye. In photokeratitis, this staining shows a pattern called diffuse punctate erosions: hundreds of tiny dots scattered across the corneal surface, each one a spot where UV radiation destroyed surface cells. This pattern is distinctive. It differs from the branching, tree-like staining of a herpes eye infection or the single large defect of a corneal scratch.
The “diffuse” part is key. Because UV light hits the entire exposed surface of the eye fairly evenly, the damage is spread broadly rather than concentrated in one spot. Doctors also check the front chamber of the eye for signs of deeper inflammation. In photokeratitis, this deeper involvement is typically absent, which helps distinguish it from more serious conditions.
How It Differs From Pink Eye and Other Red Eye Conditions
Photokeratitis looks a lot like several other eye conditions on the surface, but the combination of symptoms and history sets it apart. Pink eye (conjunctivitis) causes redness and tearing but rarely involves significant pain or light sensitivity. A corneal abrasion from a physical scratch causes similar pain and tearing, but the damage is localized to one area rather than spread across the whole cornea.
The critical clue is always the exposure history. If your red, painful, light-sensitive eyes showed up 6 to 12 hours after a day of skiing without goggles, hours of welding without a mask, or extended time on highly reflective water or sand, photokeratitis is the likely culprit. Snow reflects up to 80% of UV radiation, which is why “snow blindness” is the most well-known form of this condition.
Common Causes
Photokeratitis results from overexposure to UV-B and UV-C radiation. The most frequent triggers include prolonged sun exposure at high altitudes or in snowy environments, unprotected arc welding (sometimes called “welder’s flash”), tanning beds used without proper eye protection, and spending extended time near water or sand that reflects UV light upward past the brim of a hat or sunglasses. Even attending outdoor events with certain types of UV-emitting stage lighting has caused documented outbreaks.
Recovery Timeline
The cornea is one of the fastest-healing tissues in the body, which works in your favor. Most cases of photokeratitis resolve within one to three days as new epithelial cells replace the damaged ones. The worst of the pain and light sensitivity usually peaks within the first 24 hours and then steadily improves. During recovery, cool compresses, staying in dim environments, and avoiding contact lenses can help with comfort. Artificial tears help keep the healing surface lubricated.
If pain or vision changes persist beyond two days after exposure, that warrants medical attention, as it could indicate deeper corneal damage or a different diagnosis altogether. Repeated episodes of photokeratitis over time can contribute to longer-term surface problems, so prevention with UV-blocking eyewear matters more than any treatment after the fact.