"Uveitis" is a broad term used to describe any inflammation inside the eye. If it is primarily located in the front part of the eye, your doctor may call it "iritis". Other parts of the eye may be inflamed as well, such as in scleritis, which is inflammation of the eye wall.
The cause of uveitis is the topic of much research; it is an autoimmune reaction, which is when a person’s own immune system begins to react against the eye. Some cases are "idiopathic", meaning it is not known what triggered the inflammation, and there are no associated systemic or whole-body problems. In other cases, a disease such as sarcoidosis or rheumatoid arthritis may be causing the inflammation. More rarely, infections can cause uveitis; these can usually be detected by a thorough history, physical examination, and diagnostic studies such as blood work or x-rays.
Uveitis is not your usual "pink eye", and does not respond to antibiotic drops. Anti-inflammatory drops (typically steroid drops) are often effective in controlling the inflammation. If these drops are not effective, then other options may be considered. More potent steroids can be given by injection next to or even into the eye itself, or taken by pill. In some patients, the inflammation is so severe that if left untreated it can lead to blindness; in these patients, other anti-inflammatory or immunosuppressive medicines may be recommended. In most cases the disease can be treated effectively and vision preserved.