An epiretinal membrane, or macular pucker, is a thin layer of scar tissue that can grow over the surface of the retina.  As this tissue contracts, the retinal surface can become wrinkled or distorted.  This creates symptoms of distortion (images are bent or wavy) or blurry vision in the patient.  Most epiretinal membranes are mild and do not require surgery, however, when an epiretinal membrane progresses to the point where it is causing symptoms, surgery (vitrectomy) to remove the membrane can be performed.  A gas bubble and post-operative positioning is not usually needed.