Diagnostic and therapeutic dilemmas in ocular toxoplasmosis

Ocular toxoplasmosis, a leading cause of visual handicaps in young people, represents a late manifestation of congenital infection in the majority of cases. Ocular involvement in acquired toxoplasmosis has been repeatedly reported and shows that toxoplasmic retinitis may develop in the wake of acquired infection. The diagnosis of ocular toxoplasmosis is mainly clinical since serologic tests are positive for a considerable percentage of the general population and are not indicative for ocular involvement. The demonstration of local synthesis of toxoplasma antibodies in the eye by intraocular fluid analysis is a valuable diagnostic tool. The application of the polymerase chain reaction, in which the parasite's DNA is detected, may be expected to change the diagnostic repertoire drastically in the future. The need for appropriate therapy for patients with ocular toxoplasmosis is a matter of continued debate: the majority of the medications used for treatment have potentially serious side effects and the efficacy of treatments has not been clarified in previous studies. Recently, a prospective multicenter study to evaluate the efficacy of current therapeutic strategies for ocular toxoplasmosis was performed in The Netherlands and included 106 patients with active ocular toxoplasmosis. The principal conclusion of this study is that only drug therapy with pyrimethamine had any perceptible influence on any aspect of ocular toxoplasmosis, but this effect may not be worth the risk of side effects except in fovea threatening lesions.