Analysis of aqueous humor in uveitis with toxoplasmosis

Background: Despite many clinical examinations and laboratory tests, the cause of uveitis is very often not discovered. The examination of local intraocular antibody production is a valuable additional diagnostic means. Patients and methods: Aqueous humor was obtained from 46 eyes with severe uveitis: retinochorioiditis (n = 27), intermediate uveitis (n = 11), iridocyclitis (n = 5), and panuveitis (3). With the enzyme-linked immunosorbent assay (ELISA) the antibodies against Toxoplasma gondii were measured in aqueous humor and serum and the intraocular antibody production was calculated by the formation of an antibody index (Al). As the Al values are corrected for possible polyspecific immune response, the Al index is more sensitive than the Goldmann-Witmer index. Results: An intraocular antibody synthesis against T. gondii could be confirmed in 20 eyes. The serum antibody concentration against T. gondii was in the reference range in 45 patients and only one patient had a very high increase of antibodies. In nine of 20 eyes, intraocular synthesis of antibodies against T. gondii was unexpected due to the lack of clinical evidence. Conclusions: The aqueous humor analysis is more reliable than the proof of serum antibodies, and it helps to increase the number of eyes with uveitis in which a specific therapy can be established.