Uveitis is inflammation anywhere in the pigmented inside lining of the eye, known as the uvea or uveal tract.
The uveal tract consists of three structures: the iris, the ciliary body, and the choroid.
The iris, the colored ring around the black pupil, opens and closes to let more or less light into the eye, just like the shutter in a camera.
The ciliary body is the set of muscles that, by contracting, allows the lens to become thicker so the eye can focus on nearby objects. By relaxing, the ciliary body allows the lens to become thinner so the eye can focus on distant objects. This process is called accommodation.
The choroid, which lines part of the back part of the eyeball, extends from the edge of the ciliary muscles to the optic nerve at the back of the eye. The choroid lies between the retina on the inside and the sclera on the outside. The choroid contains both pigmented cells and blood vessels that nourish the inside parts of the eye, particularly the retina.
Part or all of the uveal tract may become inflamed. Inflammation limited to part of the uvea is named according to its location. Anterior uveitis is inflammation in the front of the uveal tract, including the iris. Intermediate uveitis is inflammation in the middle of the uveal tract. Posterior uveitis is inflammation in the back of the uveal tract and can involve the retina and choroid. Panuveitis is inflammation that affects the entire uveal tract. Sometimes, uveitis is referred to by the name of the specific part that is inflamed—for example, iritis (inflammation of the iris), choroiditis (inflammation of the choroid), or chorioretinitis (inflammation that involves both the choroid and the overlying retina). Inflammation of the uvea is limited to one eye in many people with uveitis but may involve both eyes.
The inflammation has many possible causes. Some causes are limited to the eye itself, and others are disorders that affect the entire body. In most people, no cause is identified, and they are said to have idiopathic uveitis (or uveitis of unknown cause). Many people with uveitis have a disorder that also affects organs elsewhere in the body. These include inflammatory diseases, such as Behçet syndrome, ankylosing spondylitis, juvenile idiopathic arthritis, sarcoidosis, reactive arthritis, inflammatory bowel diseases (Crohn disease and ulcerative colitis), and, among Asians and some Hispanics, Vogt-Koyanagi-Harada disease. Some people have widespread infections, such as tuberculosis, syphilis, or Lyme disease. Other possible causes include infections that may affect only the eye, such as herpes (herpes simplex virus) infection, shingles (varicella-zoster virus), toxoplasmosis, and cytomegalovirus. Cytomegalovirus occurs mainly in people infected with human immunodeficiency virus (HIV)/AIDS. Eye injuries are a common cause of anterior uveitis. Although rare, some drugs (such as pamidronate, rifabutin, sulfonamide antibiotics, and cidofovir) can cause uveitis.
The early symptoms of uveitis may be mild or severe, depending on which part of the uvea is affected and the amount of inflammation.
Uveitis can rapidly damage the eye. It can cause long-term, vision-threatening complications, such as swelling of the macula, damage to the retina, glaucoma, and cataracts. Many people have only one episode of uveitis. Others have periodic recurrences over months to years.
Diagnosis and Treatment
A doctor bases the diagnosis on the symptoms and a physical examination. During the examination, the doctor uses a slit lamp. A slit lamp is an instrument that enables the doctor to examine the eye under high magnification. If the doctor suspects a disorder that also affects other organs, appropriate tests are done.
Treatment must start early to prevent permanent damage. Treatment almost always includes corticosteroids, usually given as eye drops. Corticosteroids can also be taken by mouth or injected into the eye. Drugs to dilate the pupils, such as homatropine drops, are also used. Other drugs may be used to treat specific causes of uveitis. For example, if infection is the cause, drugs may be given to eliminate the infecting organism. Occasionally, other treatments are necessary, such as surgery, use of a laser, injection of drugs into the eye, or drugs taken by mouth or injected by vein (intravenously) that suppress the immune system (immunosuppressants).
Last full review/revision October 2012 by Emmett T. Cunningham, Jr., MD, PhD, MPH