Uveitis is a general term that refers to inflammation of the part of the eye known as the uvea.
The uvea is a relatively thick, strong layer of fibrous tissue that encloses and protects the eyeball. It consists of three parts: the iris, the ciliary body, and the choroid.
There are three types of uveitis, classified according to the part of the uvea that is affected. Anterior uveitis, which affects the front part of the eye, is also sometimes called iritis since the iris is part of the front of the eye. Intermediate uveitis, also known as pars planitis or cyclitis, refers to inflammation of tissues in the area just behind the iris and lens of the eye. Posterior uveitis, also known as choroiditis, refers to inflammation of the choroid, the back part of the uvea. Posterior uveitis may affect the retina and/or the optic nerve, and may lead to permanent loss of vision.
Posterior uveitis is the rare form of the disorder and is the type of uveitis most associated with loss of vision. The other two forms are more common, and more frequently result in acute symptoms, but only rarely cause vision loss.
Posterior uveitis is usually, but not always, painless. Symptoms typically include “floaters”, small specks, flakes, or clouds that move through the field of vision, and decreased vision. While anterior uveitis often causes eye pain and redness, light sensitivity, and blurred vision, the symptoms of posterior uveitis are more subtle.
Uveitis can lead to other complications, including glaucoma, cataracts, or retinal detachment. Early detection and treatment is important to reduce the risk of permanent vision loss.
Posterior uveitis can have infectious or noninfectious causes. Infectious causes include bacterial, fungal, parasitic, and viral infections. Noninfectious causes include immunologic problems, allergies, malignancies, and unknown causes.
One report suggests that about 60% of cases are caused by problems intrinsic to the eye itself and that the other 40% of cases are the result of associated autoimmune disorders, infections, and/or trauma. Some of the disorders with which posterior uveitis is sometimes associated are Behcet’s syndrome, ankylosing spondylitis, Lyme disease, sarcoidosis, and psoriasis. Among children, the disorder is frequently associated with juvenile rheumatoid arthritis.
Posterior uveitis occurs as an isolated condition or as part of other disease affecting body systems (systemic). This condition affects males and females in equal numbers. It can strike at almost any age, although it appears most often to occur between the ages of 20 and 50. According to one estimate, chronic, non-infectious posterior uveitis affects 175,000 people in the United States and 800,000 people worldwide. Almost 80% of cases of uveitis affect the front (anterior) portion of the eye.
The first step in diagnosis is to determine the role, if any, of other immunological and/or infectious conditions in the development of the disorder. Blood studies for infectious agents such as herpes virus, toxoplasmosis, toxocariasis and spirochetes are helpful. Chest x-rays may detect sarcoidosis or tuberculosis. If systemic or central nervous system involvement is present or large cell lymphoma is suspected, neuroimaging studies and lumbar puncture may be used.
It is important to identify and treat an underlying infection or immunological disorder before initiating other treatment. Steroids administered intravenously are often used as a treatment for posterior uveitis. However, long-term use of systemic corticosteroids carries with it the risk of increased pressure in the eye (glaucoma) and cataracts, so the patient must be followed closely.
In April of 2005, the FDA announced the approval of the orphan product Retisert (an implant) for the treatment of chronic, non-infectious posterior uveitis. The implant, a tiny drug reservoir, delivers approximately two-and-a-half years of the anti-inflammatory corticosteroid, fluocinolone acetonide, directly to the back of the eye. For information, contact the manufacturer:
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Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
For information about clinical trials sponsored by private sources, contact:
Currently, the National Eye Institute is sponsoring clinical trials involving posterior uveitis. Two of these studies involve the use of a monoclonal antibody as a treatment for posterior uveitis. Monoclonal antibodies are genetically engineered proteins designed to affect a specific target or biochemical reaction within the body. In these trials, the monoclonal antibody is known as daclizumab and it inhibits a specific chemical reaction needed by lymphocytes to produce inflammation. For information about these and other current trials, visit the ClinicalTrails.gov web site or contact the NIH Patient Recruitment Office (see above).
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FROM THE INTERNET
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