Epiretinal membrane is a disease of the eye in response to changes in the vitreous humor or more rarely, diabetes. It is also called macular pucker.
Sometimes, as a result of immune system response to protect the retina, cells converge in the macular area as the vitreous ages and pulls away in posterior vitreous detachment (PVD). PVD can create minor damage to the retina, stimulating exudate, inflammation, and leucocyte response. These cells can form a transparent layer gradually and, like all scar tissue, tighten to create tension on the retina which may bulge and pucker (e.g. macular pucker), or even cause swelling or macular edema. Often this results in distortions of vision that are clearly visible as bowing when looking at lines on chart paper (or an Amsler grid) within the macular area, or central 1.0 degree of visual arc. Confirmation of the problem, as well as the display of its size, is done using the Optical Coherence Tomography (OCT).
Usually it occurs in one eye first, and may cause binocular diplopia or double vision if the image from one eye is too different from the image of the other eye. The distortions can make objects look different in size (usually larger = macropsia), especially in the central portion of the visual field, creating a localized or field dependent aniseikonia that cannot be fully corrected optically with glasses. Partial correction often improves the binocular vision considerably though. In the young (under 50 years of age), these cells occasionally pull free and disintegrate on their own; but in the majority of sufferers (over 60 years of age) the condition is permanent. The underlying photoreceptor cells, rod cells and cone cells, are usually not damaged unless the membrane becomes quite thick and hard; so usually there is no macular degeneration.