Fuchs' heterochromic cyclitis.
Fuchs' heterochromic cyclitis (FHC) is a chronic anterior segment inflammatory syndrome that accounts for 2 to 3% of all uveitis cases. The etiology is unknown, but Herpes simplex, ocular toxoplasmosis and rubella infection have been implicated in the pathogenesis of the disease. It occurs more commonly in the third and fourth decades of life with an equal gender distribution. Patients are usually asymptomatic but may present with floaters and blurry vision. There is a mild but persistent anterior chamber reaction with diffuse and characteristic white stellate keratic precipitates. Iris and trabecular meshwork show abnormal vessels that may sometimes lead to a hyphema. Synechia formation is uncommon. Heterochromia is considered an important feature and accounts for the name, but it is variable depending on the intensity of the anterior stromal atrophy, initial iris color and amount of pigment in the iris pigmented epithelium. Progression of the disease is associated with cataract formation and glaucoma. Anti-inflammatory treatment is not indicated for the low-grade anterior chamber reaction seen in Fuchs' patients. Occasionally, a short course of corticosteroids is indicated if a symptomatic exacerbation occurs. The long-term prognosis is good, and patients usually maintain a visual acuity of 20/40 or better.