Differential diagnosis of CMV retinitis.

Diagnosis of cytomegalovirus retinitis (CMVR) is usually made by retinal examination by an experienced ophthalmologist. The characteristic appearance of the infection is distinctive enough that recourse to ancillary tests or diagnostic procedures is rarely needed. However, atypical cases of CMVR or infections with other organisms in individuals at high risk for CMVR may require invasive diagnostic testing of ocular fluids or tissues using comparative antibody titers, amplification of organismal DNA or RNA, culture, or histology. A small number of other organisms are frequent enough as causes of intraocular infection that the typical appearances of these infections have become known. Familiarization of the clinician with the expected clinical presentation of various infections can facilitate diagnosis, selection of confirmatory diagnostic tests, and empiric therapy.