An epiretinal membrane (ERM) is a thin sheet of scar tissue that forms over the surface of the macula. This condition is known by many other names, including cellophane maculopathy, preretinal fibrosis, and macular pucker. In most cases, the scar tissue is mild and doesn’t cause any significant problems. In some people, however, the scar tissue becomes thicker and can cause problems with visual distortion and decreased central vision.
Most ERMs develop following a posterior vitreous detachment. The vitreous is the jelly-like substance which fills the back cavity of the eye. As part of the aging process, the vitreous liquefies and may separate from the retina. This can cause microscopic damage to the surface of the retina, with resulting scar tissue or ERM formation. Eye trauma, inflammation inside the eye, diabetic retinopathy, and history of retinal tear or detachment may also promote ERM formation.
Typically, a mild ERM produces no symptoms. If it worsens, it may cause blurred central vision and visual distortion.
An ERM is usually diagnosed during a dilated eye exam. The outside of the eye looks completely normal and there is no pain associated with the condition.
In most cases, an ERM will appear as a faint sheen overlying the macula. If it progresses, the membrane can become thicker and denser. Eventually, it may cause distortion of the retinal vessels and even some swelling of the macula.
Most ERMs require no treatment at all. In moderate to advanced cases, usually when vision drops to the level of 20/40 or worse, a vitrectomy may be recommended. This microsurgical procedure is the only way to remove an ERM. This is done in the operating room, usually under local anesthesia. The procedure typically lasts between 45 and 60 minutes. The vitreous gel in the back of the eye is removed, and the scar tissue is carefully dissected from the macula. The gel is then replaced with a saline solution. In successful cases, vision usually improves by about 50%, although this may take several months. The major side effect of vitrectomy surgery is development of a cataract, which may need to be removed later on.
No treatment is available to prevent an ERM.
Occasionally, an ERM is associated with swelling of the retina. Research is being done to find the best way to treat this type of swelling.