Sunday, November 16, 2008

Uveitis Facts

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).

Facts about Uveitis:

  • Chronic uveitis is more common than acute and recurrent uveitis.

  • Chronic uveitis is especially common in patients with intermediate uveitis.

  • Nongranulomatous uveitis occurs more frequently than does granulomatous uveitis, especially in patients with anterior uveitis.

  • Noninfectious uveitis is more common than is infectious uveitis, particularly among patients with panuveitis and anterior uveitis.

  • Bilateral uveitis (in both eyes) is more common than unilateral uveitis (one eyes) in patients with panuveitis and intermediate uveitis.

  • Anterior and posterior uveitis cases have approximately equal distribution of unilateral and bilateral cases.

  • The mean age of onset is clearly younger in patients with intermediate uveitis, 30.7 years (+ 15.1 years).

  • Despite the huge advances in diagnostic techniques and the determination of ophthalmologists worldwide to reach and etiologic diagnosis, many cases remain in the idiopathic category (35% to 50%). The term idiopathic uveitis denotes that the intraocular inflammation could not be attributed to a specific ocular cause or to an underlying systemic disease, and it was not characteristic of a recognized uveitis entity.

  • The most common causes of anterior uveitis are idiopathic (37.8%); seronegative HLA-B27-associated arthropathies (21.6%), juvenile rheumatoid arthritis (10.8%), herpetic uveitis (9.7%) sarcoidosis (5.85%), Fuchs' heterochromic iridocyclitis (5.0%), systemic lupus erythematosus (3.3%), intraocular lens-induced persistent uvietis (1.2%), Posner-Schlossman syndrome (0.9%), rheumatoid arthritis (0.9%). Syphilis, tuberculosis, phacogenic uveitis, Lyme disease, and collagen vascular disease (Wegener's granulomatosis, polyarteritis nodosa, and relapsing polychondritis) caused some cases of anterior uveitis.

  • The most common causes of intermediate uveitis are idiopathic (69.1%), sarcoidosis (22.2%), multiple sclerosis (8.0%), and Lyme disease (0.6%).

  • The most common causes of posterior uveitis are toxoplasmosis (24.6%), idiopathic (12.3%), cytomegalovirus retinitis (11.6%), systemic lupus erythematosus (7.9%), birdshot retinochoroidopathy (7.9%), sarcoidosis (7.5%), acute retinal necrosis syndrome (5.5%), Epstein-Barr virus retinochoroiditis (2.9%), toxocariasis (2.5%), Adamantiades-Bechet's disease (2.0%), syphilis (2.0%), acute posterior multifocal placoid pigment epitheliopathy (2.0%), and serpiginous choroidopathy (1.65%). Other causes of posterior uveitis include punctate inner choroidopathy, multiple evanescent white-dot syndrome, multiple sclerosis, temporal arteritis, presumed ocular histoplasmosis, fungal retinitis, and leukemia.

  • The most common causes of panuveitis are idiopathic (22.2%), sarcoidosis (14.1%), multifocal choroiditis and panuveitis (12.1%), ABD (11.6%), systemic lupus erythematosus (9.1%), syphilis (5.5%), Vogt-Koyanagi-Harada syndrome (5.5%), HLA-B72 associated (4.5%), sympathetic ophthalmia (4.0%), tuberculosis (2.0%), fungal retinitis (2.0%). Other causes of panuveitis include bacterial panophthalmitis, intraocular lymphoma, relapsing polychondritis, polyarteritis nodosa, leprosy, dermatomyositis, and progressive systemic scelerosis.

The above-mentioned percentages and figures were obtained from a study of 1237 uveitis patients referred to the Uveitis and Immunology Service of the MEEI, Harvard Medical School, from 1982 to 1992. These figures were found to be similar to the results of other studies of tertiary referral centers from different parts of the world., especially those of developed countries.