This is an inflammation inside the eye that involves either the structures in the front of the eye (the iris and ciliary body) or the choroid in the back of the eye. Most people with uveitis have inflammation of the iris (the colored part of the eye). This is called iritis. When the iris is inflamed, it tends to hurt and spasm when subjected to bright lights. This pain is called photophobia. We can detect uveitis when looking inside the eye because we can actually see individual inflammatory cells (white blood cells and macrophages) floating around in the anterior chamber of the eye. The number of these cells visible correlates with the severity of inflammation. If the inflammation is bad enough, the pupil can become irregularly shaped from iris synechiae formation. There are many causes for an episode of uveitis, though at least half of them occur idiopathically with no known cause. Inflammatory conditions like rheumatoid arthritis and sarcoidosis may cause uveitis. People who have HLA-B27 positive conditions like ankylosing spondylitis and inflammatory bowel disease are also prone to uveitis. Viral infections from zoster (shingles) can cause uveitis, especially with repeat outbreaks. Rare infections such as Lyme disease, syphilis, and tuberculosis can all cause uveitis as well (though we seldom see these infections in this area). Treatment is primarily with steroid eye drops (to cool down the inflammation) and a dilating cycloplegia drop (for pain control and to avoid synechiae formation). The first time a person has uveitis, no further workup is usually indicated. However, recurrent or severe bouts may instigate additional testing and consultation with a rheumatologist to look for underlying pro-inflammatory conditions.