Epi-retinal membrane (ERM) or macular pucker is a cellophane-like membrane that forms over the macula. It is typically a slow-progressing problem that affects the central vision by causing blur and distortion. As it progresses, the traction of the membrane on the macula may cause swelling.
ERM is seen most often in people over 75 years of age. It usually occurs for unknown reasons, but may be associated with certain eye problems such as: diabetic retinopathy, posterior vitreous detachment, retinal detachment, trauma, and many others.