An epiretinal membrane (ERM) is a medical condition where a thin layer of scar tissue forms over the central part of the retina, known as the macula. This condition is also sometimes called macular pucker or cellophane maculopathy due to its transparent, wrinkled appearance. The formation of this tissue causes traction, or pulling, on the underlying retinal surface, which leads to distorted and blurred central vision. Although common, especially in older adults, the severity of the membrane’s effect on vision can vary significantly.
What Is an Epiretinal Membrane?
An epiretinal membrane is a sheet of fibrocellular material that develops on the inner surface of the retina, specifically over the macula. The macula is a highly specialized area responsible for sharp, detailed central vision, necessary for tasks like reading and recognizing faces. The membrane is composed of various cells, including glial cells and retinal pigment epithelial cells, which proliferate and form a semi-translucent sheet. The location of this scar tissue makes the condition visually significant, as any structural disruption here directly impacts the quality of central sight.
The membrane adheres tightly to the internal limiting membrane (ILM), the innermost layer of the retina. As the cellular material within the membrane matures, it begins to contract, similar to how scar tissue shrinks elsewhere in the body. This contraction exerts a tangential pulling force on the macula, causing the retinal layers to wrinkle, fold, or pucker. This mechanical distortion, known as traction, is the direct cause of the visual symptoms experienced by a patient.
Recognizing the Symptoms and Visual Effects
The visual changes caused by an epiretinal membrane arise from the physical distortion of the macula. The most characteristic symptom is metamorphopsia, where straight lines appear wavy, bent, or distorted. Patients also commonly report blurred central vision and difficulty seeing fine details, making tasks like reading challenging. The degree of vision loss can range from mild, where the patient is asymptomatic, to significant impairment. Because the condition affects the macula, it does not typically cause a total loss of sight or affect peripheral vision.
Ophthalmologists often use an Amsler grid, a simple checkerboard pattern, to help patients detect and monitor metamorphopsia. If the lines appear wavy or distorted when viewed with one eye, it indicates a problem with the central retina. Diagnostic imaging, such as Optical Coherence Tomography (OCT), is used to visualize the membrane and precisely measure the extent of retinal wrinkling and thickening.
Underlying Causes and Risk Factors
The development of an epiretinal membrane is broadly categorized into two types: idiopathic and secondary. The idiopathic form is the most common, meaning its cause is not directly attributable to a specific eye disease other than age-related changes. The primary mechanism associated with idiopathic ERM is Posterior Vitreous Detachment (PVD), which occurs when the vitreous gel separates from the retina.
During PVD, cells can be released and subsequently multiply on the retinal surface, initiating the formation of the membrane. Secondary ERMs develop as a complication of other pre-existing eye conditions or procedures. Significant risk factors include previous eye surgeries, such as cataract removal or retinal detachment repair. Other underlying retinal pathologies, like diabetic retinopathy, retinal vein occlusions, intraocular inflammation (uveitis), or trauma, can also trigger membrane formation. The risk of developing an ERM increases with age, with prevalence rising significantly in individuals over 75.
Treatment Approaches
For many people, an epiretinal membrane is mild and does not cause significant vision problems, requiring no immediate intervention. In these cases, the standard approach is observation through regular eye examinations to monitor for progression. Eye drops, medications, or dietary supplements have no effect on shrinking or removing the scar tissue.
When the membrane progresses to cause bothersome visual distortion, interfere with daily activities, or lead to a measurable decrease in vision, surgical intervention is the only viable treatment. The surgical procedure is called a vitrectomy with membrane peel. This procedure involves the surgeon making tiny incisions to access the inside of the eye and remove the vitreous gel.
Once the vitreous is removed, the surgeon uses micro-instruments to carefully peel the epiretinal membrane layer off the surface of the macula. The goal of this peeling is to immediately relieve the traction and allow the wrinkled macula to flatten out. Following the surgery, vision is initially blurred, and improvement occurs gradually as the retina heals. While a significant improvement in distortion is common, full visual recovery can take three to six months, and in some cases, up to a year.