Epi-retinal Membrane Can Cause Severe Vision Impairment
Epiretinal membrane is known by many names including: epimacular membrane, surface-wrinkling retinopathy, cellophane maculopathy and preretinal macular fibrosis.
The gel like fluid inside the back of the eye, the vitreous, is composed of microscopic fibers that attach to the surface of the retina. With increasing age the vitreous shrinks and pulls away from the retina. This complication, called a posterior vitreous detachment (PVD) causes vitreous floaters, but usually no other adverse effects. However, sometimes when the vitreous pulls away from the retina, damage occurs to the inner surface of the retina. This sometimes forms scar tissue, or an epi-retinal membrane, on the inner surface of the retina. This scar tissue sometimes causes the retina to get distorted or wrinkled (or “pucker”). If the scar tissue forms over the macula the central vision becomes blurred or distorted.
Symptoms of Epi-retinal Membrane
In the early stages, an epiretinal membrane may be asymptomatic, or it may create only a mild reduction in visual acuity. Its progression may cause metamorphosia (a visual distortion) and lead to severe visual impairment. A patient’s visual acuity can range from 20/20 to 20/200 with an epiretinal membrane.
Signs of Epiretinal Membrane
A patient cannot see any visible signs of epiretinal membrane because the condition is limited to the inside of the eye. A patient will only notice vision problems (distortion and blur) that lead the person to an eye doctor, who will be able to see the signs inside the eye.
Diagnosis of Epiretinal Membrane
An epiretinal membrane has a characteristic clinical appearance known to trained eye doctors and the diagnosis is made by an eye doctor during a dilated retina exam, retinal photography or scanning laser ophthalmoscopy. In some cases Fluorescein Angiography may be used to determine if swelling is present and to rule out other retinal diseases. Optical Coherence Tomography (OCT), which provides a scan of the retina (similar to an MRI, but with 200% higher resolution) can be very useful in identifying epiretinal membrane irregularities along the retinal surface.
Prognosis of Epiretinal Membrane
Most patients diagnosed with epiretinal membrane remain stable and vision does not get progressively worse. Epiretinal membrane is usually unilateral (one eye only), although it may affect the other eye later.
Treatment for Epiretinal Membrane
In most cases, little can be done to improve visual acuity. Most patients only suffer a minimal reduction in vision or have slight metamorphopsia (distortion of visual images). In severe cases, vision may drop to 20/100 or worse and a vitrectomy surgery to remove the epiretinal membrane may be recommended. Eye drops, medications or eyeglasses will not correct the loss of vision. During vitrectomy surgery, the vitreous gel is removed and the epiretinal membrane is peeled from the surface of the retina using microscopic forceps. Removing the vitreous is not harmful to the function of the eye. Vitrectomy surgery is an outpatient procedure usually performed under local anesthesia. This procedure is very intricate with its own set of complications, and is therefore reserved for those patients for whom there are no alternatives.