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NORD is very grateful to Dr. Patricio A. Pacheco, Bsc, MD, MRCOphth, Senior Clinical Fellow /Uveitis Service, Moorfields Eye Hospital, London, UK for assistance in the preparation of this report.
Although pars planitis is generally benign, there can be significant vision loss in extreme cases. It is an immunological disorder of the eye characterized by inflammation of a part of the uvea, the layer of tissue between the sclera and the retina, the membranes protecting the eyeball. The uvea, in turn, is made up of three portions: the iris, the ciliary body, and the choroid. In addition, the uvea contains many of the blood vessels that supply the eye.
The pars plana is a narrow section of the ciliary body, inflammation of which is known as pars planitis. In association with the inflammation or immunological response, fluid and cells infiltrate the clear gelatin-like substance (vitreous humor) of the eyeball, near the retina and/or pars plana. As a result, swelling of the eye or eyes can also occur, but more importantly blurred vision and progressive increase in the vision of floaters is reported as main symptoms by patients suffering this condition as a result of the infiltration of the vitreous humor.
The inflammation occurs in the intermediate zone of the eye; that is, between the anterior part(s) of the eye (iris) and the posterior part(s), the retina and/or choroid. It has therefore been designated as one of the diseases of a family of intermediate uveitis.
In some cases, the disturbance of vision may be slightly progressive.
The symptoms of pars planitis include blurred vision and dark floating spots that intrude upon clarity of eyesight. Swelling can occur inside the eye, particularly on the peripheral retina or macula that may lead to decreased vision. Glaucoma may occur as well.
The clinical picture may be complicated by cataracts, retinal detachment, or fluid within the retina (macular edema)
More often the examining ophthalmologist (specialist in diseases of the eye) will see clusters of white blood cells trapped within the eyeball that are called snowballs. The term physicians may use for these is inflammatory exudate. These are clusters of white blood cells trapped within the eyeball. If these clusters are located on the pars plana, they are known as snowbanks.
Pars planitis is thought to be an autoimmune disorder. An autoimmune reaction causes the inflammation that is thought to cause symptoms of this disorder.
Autoimmune disorders are caused when the body's natural defenses against foreign or invading organisms (e.g., antibodies) begin to attack healthy tissue for unknown reasons. In rare cases, pars planitis has occurred within families; however, as yet, no genetic inheritance pattern has been identified.
Some clinicians have put forward the idea that the immunological response may be the result of one of two possible causes: (1) an isolated set of events internal to the patient (endogenous), or (2) an association with some other disorder (exogenous). Among the disorders with which pars planitis has been associated are: multiple sclerosis, Lyme disease, Behcet disease, sarcoidosis, and tuberculosis, among others.
Pars planitis is an uncommon ocular disorder of children and young adults that affects males slightly more frequently than females.
The following disorders may be associated with pars planitis as secondary characteristics. They are not necessary for a differential diagnosis:
Cystoid macular edema is characterized by swelling (edema) of the central part of the retina as a result of abnormal leakage of fluid from capillaries. In pars planitis, swelling or leakage of fluid due to inflammation can affect the peripheral retina. Cystoid macular edema can often be a complication of pars planitis.
Ocular hypotension is a condition defined as lowered intraocular pressure as a result of decreased production of aqueous humor secondary to decreased blood pressure in the veins or capillaries inside the eye tissue. When this happens, vision disturbances similar to those of pars planitis may occur. This condition may in some cases be a complication of pars planitis.
Autoimmune endotheliopathy (endothelitis/ vasculitis) is an attack by the immune system on the layer of flat cells lining blood vessels (endothelium). This condition can occur in the blood vessels of the eyes as a complication of pars planitis, but can also occur alone in any part of the body. A more common name for this is: autoimmune vasculitis
Pars planitis is usually diagnosed by means of a thorough physical evaluation, detailed patient history, and specialized eye examination.
If no external causes of Pars planitis are found, treatment typically consists of corticosteroid drugs to control inflammation. If steroids are used, the patient must be carefully monitored.
If an external association of pars planitis is identified, then treatment of the associated disorder may take care of the inflammation.
Pars planitis may be accompanied by blood leaking from ruptured small blood vessels in the eye. These are generally not serious and, if necessary, can be treated by laser or cryotherapy (freezing of tissue) to seal blood vessels and arrest leakage.
Other treatments are symptomatic and supportive, as well as treatment of the complications (cataracts, glaucoma, cystoid macular edema, etc).
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.
Also website: www.uveitis.org has information regarding this condition and current trials available.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
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Report last updated: 2008/10/27 00:00:00 GMT+0