Diagnostic yield of vitrectomy in eyes with suspected posterior segment infection or malignancy

Purpose To determine the yield of diagnostic pars plana vitrectomy in eyes with suspected posterior segment inflammation or malignancy when clinical examination and systemic laboratory testing did not yield a specific diagnosis. Design Noncomparative interventional case series Participants Eighty-seven consecutive patients (90 eyes) who underwent diagnostic pars plana vitrectomy from 1989 through 1999. Interventions Vitreous samples were analyzed in a directed manner based on the preoperative clinical examination and systemic laboratory testing. Main outcome measures Diagnosis from each test performed on the vitreous samples. Results Diagnostic vitrectomy was performed alone in 6 eyes (7%) and as part of a therapeutic procedure in the remaining 84 eyes. The diagnostic tests performed most frequently included cytopathology (83%), microbiologic culture and sensitivity (43%), polymerase chain reaction (PCR) (36%), and intraocular antibody levels for T. canis (14%). Of these, intraocular antibody testing and PCR had the highest positive yield, 46% and 39%, respectively. Overall, directed vitreous analysis identified a specific cause in 35 eyes (39%). Of the 65 cases in which an underlying infection was suspected preoperatively, the procedure yielded a specific diagnosis in 27 (42%). When intraocular malignancy was considered preoperatively (71 eyes), a diagnosis of intraocular lymphoma was obtained in seven (10%). This difference between these diagnostic yields was significant ( P = 0.02, Fisher's exact test). Conclusions Diagnostic vitrectomy with directed vitreous fluid analysis yields a specific cause and guides subsequent therapy in a high percentage of cases. This procedure is a valuable adjunct in cases that cannot be diagnosed by less invasive methods.