iritis (ĪrĪˈtĭs) [key], inflammation of the iris, the pigmented portion of the eye surrounding the pupil. The condition is sometimes associated with diabetes, with rheumatic diseases such as rheumatoid arthritis, and with infections such as syphilis. Iritis may cause severe pain, a swollen, discolored iris, abnormal sensitivity to light, and blurred vision. If not quickly treated, it may result in impaired vision or blindness. Iritis is treated with antibiotics or other drugs to eliminate infection, atropine to dilate the pupil and prevent scarring, and sometimes steroids to reduce inflammation.