Epiretinal membranes (ERM) - Macular pucker

Epiretinal membranes (ERM) form as a result of pigment epithelial cells or fibroblasts (scar tissue cells) depositing themselves on the surface of the retina. Pigment epithelial cells often get to the retinal surface through tears in the retina, while fibroblasts appears as a result of vitreomacular traction (VMT) which is part of the process leading to a posterior vitreous detachment (PVD). Other causes include ocular inflammation, vascular occlusions, and trauma.

With an ERM, the traction exerted on the retina is more tangential (along the retinal surface) rather than antero-­posterior as in macular holes or VMT. With continued growth of the membrane, it will pull more and more on the retina, pulling it inwards to the center of the retina (the macula). By pulling on the surface of the retina, it will throw the retina in folds. These folds will affect the function of your retina and your vision.

What do you see? What are the symptoms?

Patients with ERM often complain of a distorted vision (lines and letters look crooked); or they notice a progressive loss of vision experienced as a difficulty to read easily and quickly. These symptoms become more apparent as the alteration in the macula increases.

How can we confirm the presence of an ERM?.

A very sensitive test to diagnose the presence of an ERM is the Amsler grid. The lines on the grid appear distorted as a result of the changes in the retina and/or the macula due to the ERM.

We can quantify the changes using other tests such as the M-chart, which is also very useful to evaluate your progression after surgery.

During your initial visit, we will perform a full eye exam including the measurement of vision and a fundus examination following the dilatation of your pupils. In order to assess the condition of your retina from its surface (where the ERM can be found) to the deeper layers (that might be damaged by sustained traction), we often perform other complementary tests such as optical coherence tomography (OCT) or fluorescein angiography.

With this information in hand, an EyeMD (ophthalmologist) can provide you with appropriate advice regarding your eye condition and the best treatment options for your particular problem.

What can be done?

Not all ERMs require a surgical intervention because not all of them progress or cause vision loss. In general, if the vision is preserved and the membrane is not located in the centre of the macula, it is often possible to postpone surgery, sometimes even permanently.

You can monitor your vision by using an Amsler grid or judging the degree to which you are having trouble reading or driving. Nevertheless, regular exams performed by your EyeMD will provide a better and more precise measure of the state of your vision.

If you experience a progressive decrease in vision, surgery may be the best option to preserve you vision.

If this is your case, this surgery usually implies a technique using a small incision in your eye (we call it vitrectomy). From this small incision the surgeon will remove the vitreous gel to reach the retinal surface and with a fine forceps, he/she will peel the epiretinal membrane away from the retina. This surgery does not require any special postoperative care other than keeping the eye clean and using some topical drops for several days. Not even special head positioning is required.

In general, after the surgery, you will progressively notice improvement of your vision over a period of 6 months. However the recovery may take longer or even been incomplete depending on the length of time the distortion was present, the degree of vision loss and, of course, your eye’s ability to heal.