Epiretinal membrane formation. Light and electron microscopic study in an experimental rabbit model.

OBJECTIVE To clarify the role of retinal glial cells in epiretinal membrane formation. METHODS We injected autologous whole blood into the vitreous cavity of albino rabbits and studied the events in the vitreoretinal interface at intervals during the course of 1 year by light and electron microscopy. RESULTS Epiretinal membranes were first found 2 weeks after the treatment. At this stage, epiretinal membranes were composed of both glial cells and macrophages. Mitotic figures of glial cells were found in the retina. The nuclei of glial cells migrated, passing through the inner limiting membrane and onto the retinal surface. At 6 months, macrophages and red blood cells disappeared from the epiretinal membranes. The epiretinal membranes became thicker with time. Finally, these epiretinal membranes were composed solely of glial cells. CONCLUSIONS At the early stage, macrophages participate with glial cells in epiretinal membrane formation; however, glial cells are the main constituent of epiretinal membranes during the late stage.