Uveitis

Uveitis is inflammation anywhere in the uvea.

The pigmented inside lining of the eye, called the uvea or 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 like the aperture of a camera lens to let light into the eye. 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 and, by relaxing, allows the lens to become thinner so the eye can focus on distant objects. The choroid, the inner lining 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 layers of blood vessels that nourish the inside parts of the eye, particularly the retina.

See the figure A View of the Uvea.

Part or all of the uvea may become inflamed. Inflammation limited to part of the uvea is named, according to its location, as anterior uveitis, intermediate uveitis, or posterior uveitis. Inflammation that affects the entire uvea is called diffuse uveitis or panuveitis. 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 that are limited to the eye itself and others that affect the entire body. In most people, no cause is identified, and they are said to have idiopathic uveitis. About 40% of people with uveitis have a disease that also affects organs elsewhere in the body. These include inflammatory diseases such as ankylosing spondylitis and juvenile rheumatoid arthritis, sarcoidosis, and widespread infections.

Symptoms

The early symptoms of uveitis may be mild or severe, depending on which part of the uvea is affected and the amount of inflammation. Anterior uveitis has the most dramatic symptoms. Severe pain in the eye, redness of the conjunctiva, sensitivity to bright light, and a decrease in vision are typical. A doctor may be able to see a small pupil with prominent blood vessels on the conjunctiva near the edge of the iris, white blood cells floating in the fluid that fills the front part of the eye (aqueous humor), and deposits of white blood cells (keratic precipitates) on the inside surface of the cornea. Intermediate uveitis is typically painless. Vision may be decreased, and the person may see irregular floating black spots (floaters). Posterior uveitis typically produces decreased vision. Floaters are also common. There may also be retinal detachment (early symptoms may include blurred vision) and inflammation of the optic nerve (symptoms include loss of vision, which may vary from a small blind spot to total blindness (see Section 20, Chapter 235)). Diffuse uveitis may produce any or all of these symptoms.

Uveitis can rapidly damage the eye; it can produce long-term, vision-threatening complications, such as swelling of the macula, glaucoma, and cataracts. Many people have only one episode of uveitis. Others have periodic recurrences over months to years.

Diagnosis and Treatment

A doctor makes the diagnosis based on the symptoms and the findings from a physical examination. If the doctor suspects a disease that also affects other organs, appropriate tests are carried out.

Treatment must start early to prevent permanent damage. Treatment almost always includes using corticosteroids, usually given as eye drops. Drugs to dilate the pupils, such as scopolamine, cyclopentolate, or atropine eye 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 bacteria or parasites.