Chorioretinal biopsy in a patient with leukaemia.

The diagnosis of necrotising viral chorioretinitis in a child with leukaemia in remission was confirmed by the presence of viral particles on electron microscopy. Biopsy from the blind eye differentiated between leukaemic infiltrates and an infectious process after further investigations initially failed to support either diagnosis. Diagnostic chorioretinal biopsy may be indicated in a blind eye when the differential diagnosis includes conditions with radically different therapeutic alternatives.