uveitis,inflammation of theuvea (or uveal tract), the middle layer of tissue surrounding theeye that consists of theiris, ciliary body, and choroid. Uveitis can affect people at any age, butonset usually occurs in the third and fourth decades of life.

Anatomical forms of uveitis

Uveitis is classified anatomically as anterior, intermediate, posterior, or diffuse.Anterior uveitis typically refers to inflammation of the iris and anterior chamber; intermediate uveitis refers to inflammation of the ciliary body and vitreous humour (the jellylike filling in the anterior portion of the eye); andposterior uveitis refers to inflammation of theretina, choroid, or theoptic disk (where theoptic nerve enters the retina). Diffuse uveitis (panuveitis) implies inflammation of the entire uveal tract.

Most cases of uveitis are idiopathic, meaning the cause cannot be determined. However, when cause can be determined, uveitis is often found to originate from an infection (viral, fungal, bacterial, or parasitic),systemicdisease (typically an autoimmune disorder), or injury to the eye. When identified, the most common cause of anterior uveitis is trauma, followed by chronic joint diseases (spondyloarthropathies), juvenile idiopathicarthritis (also known as juvenilerheumatoid arthritis), and herpesvirus infection. Causes of intermediate uveitis may includemultiple sclerosis,tuberculosis,syphilis,Lyme disease, orsarcoidosis (a systemic disease characterized by the formation of grainy lumps in tissues). The most common cause of posterior uveitis istoxoplasmosis (a parasitic infection), although in immunocompromised patients it is more likely caused by infection withcytomegalovirus,Candida, or herpesvirus. Posterior uveitis can also be caused by ocularhistoplasmosis (a fungal infection), syphilis, or sarcoidosis. In rare cases uveitis can be caused by certaindrugs, includingsulfonamides, bisphosphonates (e.g., pamidronate), orantimicrobials (e.g., rifabutin and cidofovir).

Britannica Quiz

A Visit with the Word Doctor: Medical Vocabulary Quiz

Granulomatous andnongranulomatous uveitis

Uveitis is also classified as granulomatous (persistent eye inflammation with a grainy surface) and nongranulomatous. Granulomatous uveitis is characterized by blurred vision, mildpain, eye tearing, and mild sensitivity to light. Nongranulomatous uveitis is characterized byacute onset, pain, and intense sensitivity to light and has a better recovery rate than granulomatous uveitis. Acute nongranulomatous uveitis is associated with certain viral infections, such asherpes simplex andherpes zoster, as well as with Lyme disease and trauma. It also may occur in people with autoimmune diseases linked tohuman leukocyte antigen B27 (HLA B27). Such diseases include ankylosingspondylitis,inflammatory bowel disease, psoriatic arthritis (joint inflammation occurring in patients withpsoriasis), andReiter syndrome. Chronic cases of nongranulomatous uveitis are often associated with juvenile idiopathic arthritis as well as Fuchs heterochromic iridocyclitis (inflammation of the iris and ciliary body). Chronic granulomatous uveitis may be caused by syphilis, tuberculosis, or sarcoidosis.

Diagnosis and treatment

The symptoms of uveitis may be subtle but can develop rapidly and vary, depending on the site and severity of inflammation. They can include eye redness, eye pain, blurred vision, light sensitivity, floating spots, and decreased vision.Diagnosis is made on the basis of the clinical findings. Clinical signs of uveitis include dilated ciliary vessels, cells in theaqueous humour, keratin precipitates on the posterior surface of thecornea, adhesion of the iris to the cornea (posterior synechiae), and inflammatory cells in the vitreous cavity (vitritis), sometimes with snowballs (condensations of inflammatory cells) or snowbanking (deposition of inflammatory material in the area where the iris and sclera touch). Other signs may include yellow-white lesions in the retina (retinitis) or underlying choroid (choroiditis),retinal detachment, inflammation of retinal blood vessels (vasculitis), and swelling of the optic disk. Diagnosis is often confirmed with laboratory tests in order to rule outmalignant conditions with similar symptoms, such as retinoblastoma, intraocularleukemia, or intraocularlymphoma.

Treatment depends on cause but typically includes topical or systemic corticosteroids and pupil-dilating drugs that relieve pain caused by spasms of the pupil-constriction muscle. However, long-term use of corticosteroids can have harmful side effects, which may include increasedblood pressure, renal damage, andosteoporosis. In patients with severe uveitis that is unresponsive to corticosteroids or in patients with complications associated with steroidal therapy, other types of immunosuppressant agents can be used. For example, medications that target specific mediators of the immune response have proved effective in the treatment of uveitis. In particular, molecules that block proteins known astumour necrosis factor-alpha andinterleukin-2 receptor have been shown to modulateimmune response in uveitis patients. In addition, the use of intraocular pharmacotherapy via intravitreal injection and surgical implants also can be effective; however, side effects, such ascataract formation and elevated intraocular pressure, are common. Infectious causes of uveitis require antimicrobial therapy. In some cases, vitrectomy, surgical removal of the jellylike material, or vitreous, that fills the interior of the eye cavity, may be necessary.

Patients with suspected uveitis should be examined by an eye doctor within 24 hours; if left untreated, uveitis may permanently damage vision. Uveitis may give rise to other eye conditions, such as cataract (clouding of thelens or cornea) and elevated intraocular pressure, secondary to inflammation ortopical corticosteroid use. Other complications, in addition to increased risk of retinal detachment and adhesions between the iris and lens, include the formation of blood vessels in the iris, retina, or optic nerve and the formation of fluid-filled cystlike swellings on the retina, which can damage vision.

Get Unlimited Access

Try Britannica Premium for free and discover more.

Subscribe