Experimental epiretinal membranes induced by intravitreal carbon particles.

We injected 20-nm carbon particles into the vitreous of 14 young rabbits that were killed eight to ten weeks later. Histologic examination showed partial posterior vitreous detachments, epiretinal cellular proliferation, and membranes in all eyes and retinal detachments in five eyes. Electron microscopy disclosed that the epiretinal membranes were formed mainly by Müller cell expansions, astrocytes, and macrophages. Müller cells penetrated the internal limiting membrane and removed carbon particles from the vitreous by endocytosis. The experiments indicated that gaps are produced in the internal limiting membrane by glial cells and macrophages that invade the vitreous in an attempt to remove foreign material. The experimental epiretinal membranes resembled idiopathic preretinal gliosis or macular pucker.