context: The iris is a circular, pigmented membrane that provides the eye its color and the opening in the center is the pupil of the eye. The iris is made up of muscular fibers that control the amount of light entering the pupil so that you can see clearly. The iris accomplishes this task by making the pupil smaller in bright light and larger in dim light. In some people, the iris can become inflamed. This is termed iritis. Iritis may be a consequence of trauma (traumatic iritis) or nontraumatic causes: Blunt trauma to the eye can cause traumatic inflammation of the iris. Nontraumatic iritis is frequently associated with certain diseases, such as ankylosing spondylitis, Reiter syndrome, sarcoidosis, inflammatory bowel disease, and psoriasis. Infectious causes may include Lyme disease, tuberculosis, toxoplasmosis, syphilis, and herpes simplex and herpes zoster viruses. In a large number of cases, no cause for iritis is found. Iritis usually develops quickly and generally affects only one eye. Signs and symptoms may include any or all of the following: Pain in the eye or brow region Worsened eye pain when exposed to bright light Reddened eye, especially adjacent to the iris Small or funny shaped pupil Blurred vision Headache Notify your eye doctor if any of the following signs or symptoms of iritis are present: Eye pain, including pain associated with bright light Blurred vision Redness in the eye, especially near the iris If you cannot reach your eye doctor, then seek medical attention at a hospital's emergency department. If you've been diagnosed with iritis, these are questions you may want to ask your doctor: Are there any signs of permanent damage to the eye? Are there any signs of permanent vision loss? What should I expect as my eye heals? What symptoms should I call you about between visits? Is my iritis just an eye problem or is it associated with another condition? The diagnosis of iritis is confirmed by examining the eye with a slit lamp (a special microscope designed for eye exams). Your ophthalmologist can see cells (white blood cells) and flare (particles of protein) in the fluid that is produced in the eye. Iritis requires prescription medications and follow-up visits with your eye doctor, so seeking medical care is very important. Use prescription medications exactly as prescribed. Wear dark glasses if light worsens your eye pain. Take mild analgesics, such as acetaminophen ( Tylenol) or ibuprofen ( Advil), to help control some of the discomfort. Treatment of iritis includes the use of medication in the form of eye drops or pills to allow for healing and to help decrease eye pain. Treatment of iritis includes the use of a drug (in the form of eyedrops) to dilate (widen) the pupil and to prevent spasm of the iris muscles so that the inflamed iris can rest. This allows for healing and helps decrease the eye pain. Steroid eyedrops are also prescribed unless an infectious agent (virus or bacteria) caused the iritis. Steroid eyedrops help decrease the inflammation of the iris. If the eye does not improve within a week, your eye doctor may consider prescribing steroid pills or steroid injections around the eye. The length of treatment depends on the severity of disease and how well the eye improves with the treatment. In all cases of iritis, follow-up care with an eye care specialist is essential. In cases of nontraumatic iritis, your ophthalmologist will evaluate you for the presence of associated diseases. Traumatic iritis usually goes away within one to two weeks. Nontraumatic iritis may take weeks, and occasionally months, to resolve. Infectious cases of iritis will resolve once measures are taken to treat the infection. Certain cases of iritis (those associated with systemic diseases, such as sarcoidosis or ankylosing spondylitis) may be chronic or recurrent. Eye doctors may instruct certain people who are at high risk of having recurrent iritis to always have steroid eyedrops on hand so that they may begin using them at the first sign of a recurrence.