Retinal vasculitis is a nonspecific immunologic reaction of retinal arterioles or venules to various antigenic stimuli that may occur in many different systemic and local disease states. 33 There are no clear-cut clinical criteria for the diagnosis of retinal vasculitis. It may be defined, 26 however, to be present when there are vascular leakage and staining of vessel walls on fundus fluorescein angiography (FFA), with or without the clinical appearance of fluffy, white perivascular infiltrates in an eye with evidence of inflammatory cells in the vitreous body or aqueous humor. Retinal vasculitis may or may not be symptomatic. Inflammation of peripheral retinal blood vessels is typically asymptomatic, but inflammation involving macular retinal blood vessels frequently causes decreased visual acuity and focal scotomas. Associated vitreous inflammatory cells can give rise to floaters. The signs of vascular sheathing or cuffing can be found in inflammatory vascular disorders as well as in ischemic vasculopathies without inflammation. These two conditions should not be confused, as the approach to the diagnosis is different. If vascular sheathing is accompanied by vitreous cells, adjacent intraretinal edema, or infiltrates, it is more likely to be inflammatory in origin. Fundus fluorescein angiography is useful in evaluating the severity and extent of disease. Mildly inflamed vessels usually only show staining with fluorescein, whereas in more severe inflammation, dye leakage occurs as well. In occlusive vasculitis, capillary fallout is seen. If untreated, neovascularization, vitreous hemorrhage, and tractional retinal detachment may ensue. The approach to retinal vasculitis should aim at assessing the effects of vascular inflammation on the retina and visual function, and also at determining the underlying cause. Retinal vasculitis may be a major feature in certain diseases, and in others occur as a secondary phenomenon. 86 Toxoplasmosis and cytomegalovirus retinopathy (fig. 1) are examples of the latter, in which treatment of the primary pathology will result in resolution of the vasculitis. It is thus important to search the fundus for any localizing cause. If absent, one should then search for any underlying systemic disease, with the help of an internist. Retinal vasculitis may be associated with infections, malignancies, or multisystem inflammatory disorders. 86 The more commonly associated systemic diseases include Behcet's disease (BD) and sarcoidosis. 72,111 In most cases, however, the retinal vasculitis remains idiopathic and confined to the eye, 72,111 and subjecting a patient to extensive diagnostic evaluation is often unrewarding; false-positive diagnostic test results have been found in 21% of patients. 25 The workup for patients should depend on a differential diagnosis arrived at following a thorough review of systems and careful physical examination. The investigations for a patient without systemic symptoms include an FFA to determine whether the vasculitis is occlusive or nonocclusive, complete blood count, erythrocyte sedimentation rate (ESR), urinalysis, fluorescent treponemal antibody absorption test (FTA-ABS), rapid plasma reagent (RPR), and a chest roentgenogram. 25 An attempt at differentiating whether the arteries or veins are predominantly involved may aid in the differential diagnosis. 102