Etiology and diagnosis of bacterial postoperative endophthalmitis.

It is necessary to determine if postoperative endophthalmitis is of infectious or sterile etiology. Intraocular contents should be cultured and were positive in 50% of 58 eyes tested at our institute with suspected postoperative endophthalmitis. The vitreous aspirate is more sensitive than the anterior chamber aspirate in making a diagnosis. The use of a membrane filter to concentrate vitreous samples obtained at vitrectomy increases diagnostic yield. Fifty percent of culture-positive eyes yielded gram-positive organisms. Stained smears were consistent with the cultured organism in half of the cases.