An epiretinal membrane is a very thin, semi-translucent layer of scar tissue that forms above the surface of the retina. More precisely, above the center part, called the macula.
The macula comprises special sensitive nerve cells that provide our sharp central vision needed for seeing fine detail (how far you can read down the letter chart). When an epiretinal membrane develops, it can cause the underlying macula to contract and wrinkle. This translates into distorted or blurred vision and a reduction in your visual acuity, which may slowly worsen over time. Also, straight lines or letters may look wavy or bent (metamorphopsia).