What is photokeratitis?
15 September 2022
Photokeratitis is a painful, temporary eye condition caused by exposure to ultraviolet (UV) rays, usually from the sun. Photokeratitis can be compared to a sunburn, except that it affects the cornea of the eye rather than the skin. UV exposure can temporarily damage the cornea (the clear part of the eye that covers the pupil) and the conjunctiva (a clear layer of tissue that covers the inside of the eyelid and the white of the eye).
"Snow blindness" is a type of photokeratitis that occurs when UV rays reflect off snow and ice. It is most common near the north and south poles, or in mountainous regions where the air is thinner and offers less protection from UV rays.
Ultraviolet rays can damage your 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, these rays are absorbed by the ozone layer and do not harm the eyes.
In addition to direct sunlight, other sources of ultraviolet light that can cause photokeratitis include:
- sunlight reflecting into the eyes from snow, ice, water, sand or concrete;
- lamps used in tanning booths;
- laser light;
- mercury vapor lamps;
- halogen desk lamps;
- electrical sparks;
- looking directly at the sun, for example during a solar eclipse, can cause more lasting and severe damage - a burn - to the retina.
Prolonged exposure to even small amounts of UV radiation can increase the risk of developing cataracts or macular degeneration. UV exposure accumulates over time. Prolonged UV exposure can also cause elevations of tissue on the surface of the eye. These are called pingueculae and pterygium. Faithfully wearing sunglasses when outdoors can limit them.
Visible blue and violet light emitted by computers and smartphones can also be harmful to the retina and be a risk factor for macular degeneration in the future.