Biofilm on scleral explants with and without clinical infection

Biofilm is a glycocalyx matrix secreted by microorganisms that confers protection against host defenses and antimicrobial treatment. Biofilms have been implicated in the persistence of scleral buckle infections. This study aimed to evaluate the incidence of biofilm growth on scleral explants and the relationship to explant infection.

Scleral explants were obtained following removal for infection or extrusion or during repeat surgery. Explants were fixed with rhuthenium red and examined by scanning electron microscopy to visualize the glycocalyx.

A total of 28 explants were analyzed. Ten were removed because of either infection or extrusion and 18 were removed during repeat surgery. The mean time to removal of explants was 36 months in the infection/extrusion group and 12 months in the others. Biofilm was identified on five explants-two removed because of infection/extrusion and three for surgical indications. Bacterial elements were identified in all biofilms.

Biofilm was identified on explants removed because of infection or exposure and on explants removed for technical reasons at repeat surgery. This implies that bacterial contamination and biofilm formation occur without exposure of the explant, probably due to inoculation at the time of initial surgery. Biofilms may contribute to the persistence of scleral explant infections but a causative role in buckle extrusion is unproved.