Iritis is an inflammation of the colored part of the eye (iris) that can cause redness, pain, light sensitivity, and in some cases, differing pupil sizes. Left untreated, severe iritis can permanently affect vision.

Uveitis and iridocyclitis are other terms used to refer to inflammation of this part of the eye.

Most people who develop iritis have recurring episodes. Although iritis often occurs for unknown reasons, it can be linked to certain long-term (chronic) diseases that cause inflammation, such as rheumatoid arthritis, inflammatory bowel disease, or other disorders. It may also occur as a result of infection, such as a herpes infection.

Iritis is diagnosed with a complete eye exam. Treatment includes medicines given as eyedrops or by injection next to the eye.