Over the years, premacular fibrosis (PMF) has gone by many different names including cellophane maculopathy, epiretinal membrane (ERM), and macular pucker. Its nasty first cousin is proliferative vitreoretinopathy (PVR).
Premacular fibrosis (PMF) is another of several diseases that affect the macula, the center of the retina, the portion of the retina that provides the detailed vision that we use for reading, driving, and detailed work. The disease has its effects on the front side of the retina. Macular degeneration affects the underside of the retina. Although the symptoms are superficially somewhat similar, PMF is definitely not macular degeneration. It has a distinct mechanism of action, prognosis, and therapy.
The primary symptom of PMF is the gradual development of distortion in vision in one eye. 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 PMF 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. In the case of severe distortion coming from one ye, the two images cannot properly mesh and the overall experience of vision degrades.
Unlike macular degeneration, it is very rare for PMF to produce symptoms in more than one eye.
In eyes in which this process occurs, it usually follows the development of posterior vitreous separation (see separate Floaters pamphlet). Posterior vitreous separation typically occurs in a patient in their 50's or older; therefore, PMF tends to affect patients over age 50 and on the average, patients with PMF are a little younger than those with macular degeneration.
PMF results from cells migrating either out of the retina or from under the retina to the surface of the macula where they elaborate a collagen membrane. The membrane then can contract and cause distortion of the underlying macular surface the effects are similar to those that one might expect from wrinkling a photographic film, taking a picture with it in its wrinkled state, and then flattening the film before inspecting it. Vitrectomy surgery can be used to remove the premacular fibrotic membrane as an outpatient procedure performed under a local anesthetic. Most vitrectomies for PMF require less than an hour of actual operating time but may involve several hours overall spent at our outpatient surgery center. During the procedure, instruments are placed in the interior of the eye through 1.5 mm slit-like incisions in the white of the eye (sclera) a few millimeters away from the colored part of the eye. During the procedure, the eye is maintained in its normal shape by the infusion of fluid. The surgeon views the process using an operating microscope and looking down through the dilated pupil. Light is provided in the eye by a fiber-optic light pipe. First the vitreous is removed using a suctioning cutter. The premacular fibrotic membrane is then engaged with the bur on the tip of a tiny spear-like instrument and stripped from the surface of the macula using special forceps.
The amount of discomfort experienced following the surgery is quite variable. Many experience only a scratchy eye once the anesthetic wears off. Certainly a few experience nausea and even vomiting. This invariably passes after the first night. Medications are provided to control the difficulty.
The visual results of such surgery come slowly. Usually, the vision is worse than preoperatively for at least several weeks following the surgery. An improvement over the baseline vision is usually seen by four to six months, but there can still be an improvement for as long as several years following the procedure. Ultimately, a very high percentage of eyes experience a worthwhile improvement in vision.
The risks of the procedure are a rather high likelihood that in the next several years a cataract will develop in the operated eye. Such cataracts are removed in the same way as ordinary cataracts as an outpatient under local anesthetic. Of course, if the eye has already had a cataract extraction, this surgery does not produce a new cataract. All the other risks are much less frequent. There is a published 1-2% risk of a retinal detachment developing following surgery for premacular fibrosis. More than nine out of ten of these detachments are fixable but require further surgery for the repair. There is between 1 in 1,000 and 10, 000 risk of devastating intraocular infection. There are also lesser risks of transient glaucoma, vitreous and retinal hemorrhage, and some risk that the vision will not be quite as good as it was prior to the surgery even without any notable complication.
Is this surgery required to save my eye?
As mentioned above, PMF typically occurs and then often stabilizes. So far as we know, the mere presence of the membrane does not damage the underlying retina. Therefore, ordinarily one could expect the same ultimate visual result from surgery performed today versus surgery performed months or years later.