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Epiretinal Membrane

The human eye is shaped like a ball, measuring approximately one inch across, and functions like a living camera. The front portion of the eye, consisting of the cornea (the clear cover of the eye), the lens and the iris (the colored portion of the eye),acts to focus light on the back of the eye, much like the lens and aperture system of a camera focuses light on a piece of film.

The retina, similar to the photographic film itself, is a thin layer of tissue that lies against the back surface of the eye wall. The image obtained by the retina is transmitted via the optic nerve to the brain and forms the picture that we see. Unlike a camera, the image obtained by the retina is not of uniform clarity or sharpness.

Only the central portion of the retina, the macula, is sensitive enough to provide high quality vision for tasks such as reading, watching television, or driving. The macula is a very small area, with the central portion being only about the size of the head of a pin. It is only this specialized area of the retina, the macula, that is capable of the detailed vision necessary for many daily tasks. In some conditions a thin layer forms on the macula.

This thin layer of scar tissue is known as a macular pucker. Macular pucker is known by a variety of names, including epiretinal membrane, surface wrinkling retinopathy, cellophane retinopathy, and internal limiting membrane disease. All of these names relate to the fact that there is a layer of thin scar tissue on the surface of the macula which resulting in mechanical wrinkling and distortion of the retina. In most cases, the healing response is mild, and results in a very thin layer of cells lying on the surface of the retina.

These cells may be clear and may produce no significant visual disturbance. In other cases, this healing process may progress, with an overabundance of cells being produced, forming a thicker, more opaque membrane or layer of scar tissue on the surface of the macula. In most patients, even with the formation of a significant macular pucker or epiretinal membrane, there is very slow growth that takes place, and eventually the scar tissue stops proliferating or extending. With time, contraction or pulling of the cells may take place, causing a wrinkled or rippled appearance to this scar tissue.

Since the scar cells are attached to the retina, the retina itself becomes wrinkled in association with the progression of the scar. When this occurs in the central, critical portion of vision, the macula, visual symptoms may result. The symptoms of a macular pucker are common to many conditions affecting the central part of the retina. These include: distortion in lines or letters while reading, a decrease in central vision for distance and reading activities, and blurring or distortion of images when looking at television or in the theater.

The diagnosis of a macular pucker is made when an ophthalmologist performs a dilated retinal examination and examines the back of the eye. A fluorescein angiogram (injection of a dye into the vein, with photographs taken of the back of the eye) may be recommended to evaluate the situation and determine if leakage or swelling of the retina is taking place as a result of the scar tissue being present on the surface of the macula.

In most cases, no treatment is recommended for macular pucker. This is due to the fact that the visual distortion and decreased reading and distance vision is minimal in the majority of patients. Although some mild visual problems are noted, these are usually easily adjusted to and pose no limitation on full activity. In some instances, however, the distortion and vision loss may be significant. There may be an inability to perform certain daily tasks such as reading or driving.

It is at this point, that consideration for surgical repair would be entertained. Surgery would also be considered if vision loss is moderate, but there is evidence on the fluorescein angiogram of significant leakage posing a threat to permanent damage to central vision in those individuals. Repair of a macular pucker or epiretinal membrane is accomplished through use of vitreoretinal surgery.

Using microsurgical instruments, a procedure known as a vitrectomy, the microscopic removal of vitreous jell from the center of the eye, is performed. Particular attention is paid from moving any vitreous attachment from the central macular region. Specialized microsurgical instruments are then used to gently peal and remove the scar tissue from the surface of the retina, relieving the traction and reducing the distortion to the retinal surface. Unlike macular hole surgery, macular pucker surgery does not typically involve the use of an intraocular air bubble. As a result, no specialized positioning in the postoperative period is required. However, in rare instances where retinal tears or detachments occur at the time of surgery, air bubbles and special positioning may be required. The surgical procedure itself is typically performed under local anesthesia and a patient may remain in the hospital overnight or may be scheduled for ambulatory surgery, able to return home by the end of the day of the surgical procedure itself. Full visual recovery may not occur for at least 3-4 months following the procedure. As with all surgical procedures, there are potential complications and side-effects associated with repair of macular pucker. These include a small percentage of patients that develop retinal tears or detachments during the procedure or in the immediate postoperative period. These problems are usually easily repairable. In patients who have not already undergone cataract surgery, development of a cataract may occur more rapidly following vitrectomy surgery. Surgical removal of the cataract and placement of an intraocular lens is then required.

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Frequently asked questions

If I have surgery, what type of vision improvement can be expected?

Typically, a vision improvement of about 3 lines in an eye chart (or 50% improvement in vision) can be achieved. This is an "average" vision improvement, however. Recovery does vary on a patient-by-patient basis. Each individual must be evaluated and discuss with their physician the expectations for visual recovery. Some patients do achieve only a small amount of vision recovery, while others achieve a more significant degree of improvement. One of the major effects of surgery is a reduction in the degree of distortion that is often a major complaint of patients with macular pucker.

How soon will I get my vision back?

Vision improvement following macular pucker surgery typically occurs gradually as the eye heals. Usually there is some vision improvement noted in the first 6 weeks, but a final visual recovery is not achieved in many patients until a full 3 months has elapsed from the time of surgery. Once the macula has had a chance to heal and restore more normal function, a final prescription for glasses is given. For patients who have not had cataract surgery, vision may begin to exhibit gradual deterioration over 1-2 years following the vitrectomy for removal of the macular pucker, as a cataract develops. Once cataract surgery is performed, vision would then typically return to its maximal level.

Are there any restrictions on travel after macular pucker surgery?

Only patients who have intraocular air bubbles have specific restrictions on flying. Obviously, regular follow-up examinations are required in the first few weeks after surgery, and a patient must be available and close to the physician's office in order to be able to keep these follow-up appointments.

Does the scar tissue or the macular pucker ever grow back?

In a small number of cases, the macular pucker may recur or grow back as a result of reactivation of the healing process. The reason that macular puckers grow back in some patients and not in others is poorly understood. It appears that the body recognizes the surgical procedure itself as a form of injury or irritation to the retina, and restarts the healing process that caused the macular pucker in the first place. Fortunately, instances of regrowth of macular pucker are very uncommon, and stability of vision is more typically achieved after surgery