An epiretinal membrane (ERM) is a common eye condition where a layer of scar-like tissue forms on the inner surface of the retina. This fibrocellular layer is frequently found in older adults and is also known as macular pucker, preretinal macular fibrosis, or cellophane maculopathy. The formation of this membrane can lead to varying degrees of visual disturbance. While many cases cause minimal symptoms, the membrane has the potential to contract and distort the central vision.
What an Epiretinal Membrane Is
The retina is a layer of specialized nerve tissue at the back of the eye that converts light into electrical signals sent to the brain. At the center of the retina is the macula, a highly sensitive area responsible for sharp, detailed central vision used for activities like reading and recognizing faces. The epiretinal membrane forms directly over the macula.
The membrane is composed of various cells, including glial cells and fibroblasts, that accumulate and form a sheet of tissue. Over time, these cells can transform into myofibroblasts, which possess contractile properties. As the membrane contracts, it pulls and wrinkles the delicate underlying macula, a process referred to as macular pucker. This physical distortion interferes with the retina’s ability to transmit clear, accurate images.
Why the Membrane Develops
The development of an epiretinal membrane is categorized into two main groups: idiopathic and secondary. Idiopathic ERMs are the most common type, occurring without a clear, pre-existing cause or underlying eye disease. They are primarily considered a natural, age-related change.
Idiopathic ERMs are often linked to a posterior vitreous detachment (PVD), which is the separation of the vitreous gel from the retina. As the vitreous gel pulls away, it can cause small, microscopic tears in the inner surface of the retina, allowing cells to migrate and begin the scarring process. Secondary ERMs develop as a consequence of other ocular conditions.
These pre-existing issues can include diabetic retinopathy, retinal vein occlusion, retinal tears or detachment, trauma, or previous eye surgeries. Increasing age is the most significant risk factor. Studies indicate that approximately 20% of people over the age of 75 may have some evidence of an ERM.
How Vision is Affected
The most significant symptom of an ERM is metamorphopsia, which is the perception of visual distortion where straight lines appear wavy or bent. For example, a person may notice that door frames or the lines of a window blind look warped when viewed with the affected eye. The severity of the symptoms often correlates with the thickness of the membrane and the degree of traction it exerts on the retina.
Beyond distortion, patients commonly experience blurred central vision, making it challenging to see fine details required for reading small print. Some individuals also report micropsia, where objects appear smaller than their actual size, or macropsia, where objects appear larger. The visual changes caused by an ERM typically affect only central vision, leaving peripheral vision intact. While many ERMs remain stable and cause only minor visual disturbances, a progressive increase in distortion or vision loss indicates the need for intervention.
Surgical and Non-Surgical Options
For many individuals, an epiretinal membrane causes only mild visual symptoms that do not significantly interfere with daily life. In these cases, the recommended strategy is non-surgical monitoring, often referred to as “watchful waiting.” There are no eye drops, medications, or nutritional supplements proven to resolve the condition.
Surgical intervention is considered only when the visual distortion or loss of acuity substantially impacts a person’s ability to perform routine activities, such as reading or driving. The primary treatment is a procedure called a pars plana vitrectomy with membrane peel. Diagnostic tools like Optical Coherence Tomography (OCT) scans are used before surgery to confirm the diagnosis and assess the extent of the membrane’s pull on the retina.
The Vitrectomy Procedure
This surgery is performed on an outpatient basis, often using local anesthesia. During the vitrectomy, the surgeon makes tiny incisions in the white part of the eye to access the vitreous gel. The vitreous is then carefully removed and replaced with a sterile saline solution.
Once the vitreous is cleared, specialized micro-forceps are used to delicately grasp and peel the epiretinal membrane from the surface of the macula. This peeling step relieves the mechanical traction on the macula, allowing the retinal tissue to relax and flatten. After the surgery, patients typically use eye drops for several weeks to assist with healing.
Recovery and Risks
While an immediate improvement in distortion is common, full visual recovery can take several months. Potential post-operative risks are generally low. These risks include a small chance of retinal detachment and the accelerated development of a cataract, especially in patients who still have their natural lens.