Uveitis is inflammation inside the eye, specifically affecting one or more of the three parts of the eye that make up the uvea: the iris (the colored part of the eye), the ciliary body (behind the iris, responsible for manufacturing the fluid inside the eye) and the choroid (the vascular lining tissue underneath the retina). The structures of the uvea, marked here in red, are collectively known as the uveal tract. Uveitis is a serious ocular condition. It is the third leading cause of blindness worldwide, accounting in the United States for 10-15% of all blindness. Untreated or under-treated uveitis, or repeated episodes of inflammation within the eye, can lead to scarring and blinding consequences. Uveitis is a treatable condition. Patients are urged to seek consultation with a uveitis specialist, a physician with advanced training in inflammatory eye disease.

Inflammation of the uvea may occur as a consequence of diverse stimuli. These can be broadly classified according to the following mechanisms: traumatic, immunologic, infectious, and so-called masquerade. Uveitis may affect individuals of any age from infancy on. It also affects people from all parts of the world, and it is highly significant cause of blindness, accounting for 10-15% of all blindness in the United States. The average age (mean age) at presentation is approximately 40 years. Uveitis can affect people at virtually any age. Many patients in the pediatric age group, younger than 16 years, suffer devastating complications of uveitis. The peak age at onset of uveitis, in the third and fourth decades, magnifies the socioeconomic impact of uveitis on the individual and on the community.

The incidence of uveitis in the United States is approximately 15 cases per 100,000 population per year, or a total of some 38,000 new cases per year. Anterior uveitis is the most common form of uveitis, followed by posterior or panuveitis, intermediate uveitis is the least common form but still comprises a significant number of cases (4% to 17% of all cases of uveitis).