Scar tissue distorting vision
A macular pucker or epiretinal membrane (ERM) is scar tissue that forms on the macula, the portion of the retina responsible for central vision (reading, driving, etc.). An ERM results from cells migrating either out of the retina or from under the retina to the surface of the macula where they form a collagen membrane. The membrane then can contract and cause distortion of the underlying macular surface and vision. Any condition that allows cells normally found under the retina to propagate on the surface can lead to a macular pucker or epiretinal membrane, the most common being a posterior vitreous detachment or PVD (see Flashes and Floaters and Posterior Vitreous Detachment). An ERM is also sometimes called a retinal wrinkle, premacular fibrosis, and cellophane maculopathy. Its nasty first cousin is proliferative vitreoretinopathy (PVR), the number one cause of failure of retinal detachment repair surgery.
An ERM is another of several diseases that affects the macula. The ERM affects the front side of the retina while macular degeneration affects the underside of the retina. Although the symptoms are superficially somewhat similar, an ERM is definitely not macular degeneration. It has a distinct mechanism of action, prognosis, and therapy.
PVD, previous trauma to the eye, previous retinal tear or detachment, previous laser performed on the retina and/or previous inflammation in the eye.
The primary symptom of an ERM is the gradual development of distortion in vision in one eye – straight lines can appear wavy. Usually the distortion develops over weeks to months. After this initial contraction phase, the distortion often remains stable for a long period, if not indefinitely. Patients who are ready to consider surgery for an ERM often complain that they have to close the affected eye in order to effectively read. The problem is that the brain tries to mesh the images of the two eyes, and in the case of severe distortion coming from one eye, the two images cannot properly mesh and the overall experience of vision degrades. Unlike macular degeneration, it is very rare for ERM to produce symptoms in more than one eye.
The majority of patients with an ERM need no treatment. Either they have no symptoms, or have adjusted well to the mild distortion they experience. If symptoms affect activities of daily living, vitrectomy surgery can be performed. During this procedure, the vitreous gel is removed and specialized forceps are used to peel the scar tissue off the surface of the retina. (see Epiretinal Membrane Surgery). Surgery can be performed to remove the membrane, improve the retinal surface, and improve vision.