Epiretinal membrane

The source of the cells in epiretinal membranes (ERM) has been found to comprise glial cells, retinal pigment epithelial (RPE) cells, macrophages, fibrocytes, and collagen cells. These cells are found in varying proportions. Those from retinal breaks, previous retinal detachments, or cryopexy are composed mainly of dispersed RPE cells, while cells of glial origin predominate in idiopathic pathology. Laminocytes are the fundamental cell type in idiopathic ERMs. These cells are frequently found in small and dispersed numbers in eyes containing a PVD. The presence of retinal pigment cells invariable indicates proliferative retinopathy and is only seen in association with a retinal detachment or tear. The incidence of associated PVD range from 75-93%, and PVD is present in virtually all eyes with retinal breaks or retinal detachments and subsequent ERM formation. PVD can lead to retinal breaks that may liberate RPE cells that initiate membrane formation. Small breaks in the internal limiting membrane (ILM) after PVD also may provide retinal astrocytes access to the vitreous cavity, where they may subsequently proliferate. Many ERM also have ILM fragments that may be peeled separately. Finally, vitreous hemorrhage, inflammation, or both associated with a PVD also may stimulate ERM formation.