What is ultraviolet keratitis?

Ultraviolet keratitis, also known as photokeratitis, is a painful eye condition caused by exposure to ultraviolet rays, often from the sun. Ultraviolet keratitis can be compared to a sunburn, except that it affects the corneas of the eyes instead of the skin. Exposure to ultraviolet rays can temporarily damage the cornea (the clear portion of the eye in front of the pupil) and the conjunctiva (a layer of cells covering the inside of the eyelid and the whites of the eye). Damage to the eyes can occur following exposure to sunlight reflected by snow, ice, water, or sand. Staring directly at the sun, such as during a solar eclipse, can also damage the eyes.

Snow blindness is a type of ultraviolet keratitis that occurs when UV rays are reflected by snow and ice. It is more common near the North and South Poles or in mountainous regions where the air is thinner.

What are the symptoms of ultraviolet keratitis?

Symptoms may include:

  • Pain or redness in the eyes
  • Tears
  • Blurry vision
  • Swelling
  • Light sensitivity
  • Twitching of the eyelids
  • Gritty sensation in the eyes
  • Temporary loss of vision
  • Seeing halos

The symptoms may last from 6 to 24 hours, but they usually disappear within 48 hours.

What causes ultraviolet keratitis?

Ultraviolet rays from the sun or other sources can damage the eyes. In particular, UV-A and UV-B rays from the sun can cause short- and long-term damage to the eyes and affect vision. Although the sun also emits UV-C radiation, those rays are absorbed by the ozone layer and do not damage the eyes. Harmful ultraviolet radiation can also be emitted by lasers, mercury vapor lamps, lamps used in tanning beds or booths, and welding equipment. Other sources include carbon arcs, photographic flood lamps, electric sparks, halogen desk lamps, and lightning.

Long-term exposure to even small amounts of UV radiation can increase the risks of developing a cataract. The risks of developing cataracts or macular degeneration increase the longer one is exposed to solar UV rays.

People who spend a lot of time outdoors -- such as mountain climbers, hikers, and swimmers -- may be more likely to experience ultraviolet keratitis.

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