Epiretinal MembraneEdit

Epiretinal membrane (ERM), also known as macular pucker, is a fibrocellular layer that forms on the inner surface of the retina, typically at the level of the macula. It can be idiopathic, arising without an obvious preceding cause, or secondary to other eye conditions or prior eye surgery. The contraction of this semi-transparent membrane can create traction on the underlying retina, producing distortion of vision, metamorphopsia (straight lines appearing wavy), and sometimes a soft decline in acuity. In many people, ERMs remain stable and produce little or no symptoms, while in others they progressively blur or distort central vision.

This article surveys the anatomical basis, epidemiology, clinical presentation, diagnostic approaches, treatment options, and prognosis for ERMs, with attention to how clinicians decide between monitoring and intervention, and what patients can expect from care. Related concepts include the macula, the inner limiting membrane, and imaging modalities such as optical coherence tomography.

Anatomy and etiology

An ERM is a layer of cells and extracellular matrix that adheres to the inner limiting membrane (the boundary between the retina and the vitreous). It often contains glial cells, fibroblasts, and collagen. The membrane can contract over time, pulling on the macula and causing distortion of the retinal architecture. In many cases this process is idiopathic, thought to relate to age-related changes in the vitreous and retina. Secondary ERMs may follow posterior vitreous detachment, ocular inflammation, retinal tears or detachments, diabetic retinopathy, or vitreoretinal surgeries. See also posterior vitreous detachment and macular pucker for related concepts.

Epidemiology and natural history

ERM becomes more common with advancing age and is one of the more frequent macular conditions encountered in routine ophthalmic practice. Prevalence estimates vary by population and diagnostic method, but older adults are disproportionately affected. Risk factors can include a history of retinal surgery, inflammatory eye diseases, and prior retinal vascular events. Although many ERMs remain mild and asymptomatic, a subset progresses and leads to noticeable metamorphopsia and vision change. Clinicians emphasize that natural history is variable, and decisions about intervention depend on symptoms as well as imaging findings.

Clinical features

Metamorphopsia: straight lines appear curvy or wavy, particularly in the central visual field.
Decreased central visual acuity, which can fluctuate with the extent of macular distortion.
A vague distortion or blurring that may be more evident on tasks such as reading or recognizing fine details.
Fundoscopic examination may reveal a wrinkled or puckered macula and a slightly elevated, reflective surface on the inner retina.
Amsler grid testing can help patients quantify distortion at home.

Differential diagnoses to consider include macular edema, macular hole, and other causes of central vision decline. Diagnostic imaging, especially optical coherence tomography optical coherence tomography, is central to confirming the diagnosis and guiding management.

Diagnosis

Clinical examination and patient history are important initial steps.
Optical coherence tomography (OCT) is the gold-standard imaging modality for ERMs. OCT typically shows a hyperreflective, contractile membrane adherent to the inner retinal surface with traction on the fovea, resulting in thickening and distortion of the neurosensory retina.
Fundus photography can document macular changes, while fluorescein angiography is less commonly required but may be used to exclude other retinal pathology.
OCT findings help stage the severity and guide decisions about observation versus intervention.

Treatment and management

There are two primary management paths: observation for patients with minimal symptoms or stable vision, and surgical intervention for those with meaningful distortion or decreased acuity that affects daily activities.

Observation

Suitable for many individuals with mild metamorphopsia or stable vision.
Regular follow-up with visual acuity testing and OCT to monitor progression.
Education about symptom changes and realistic expectations for natural history.

Surgical treatment

Surgical removal of an ERM is typically performed via pars plana vitrectomy (PPV), with peeling of the ERM and, in many cases, the internal limiting membrane (ILM). The goal is to relieve traction and flatten the macula to improve vision and reduce distortion.

Procedure: Pars plana vitrectomy with membrane peeling. ILM peeling may be added to reduce recurrence in some cases.
Visualization: Dyes such as trypan blue or indocyanine green (ICG) may be used to assist peeling, though their use is weighed against potential risks.
Adjunct considerations: Some surgeons stage the surgery with or without ILM peeling based on patient characteristics and intraoperative findings.
Perioperative considerations: Phakic patients may experience accelerated cataract progression after PPV, and cataract removal may be necessary separately or in combination.

Potential complications (as with any intraocular surgery) include cataract progression in eyes that still have the natural lens, iatrogenic macular hole, retinal detachment, postoperative infection, and transient or persistent visual disturbances. Recurrence of ERM after peeling can occur, especially if the ILM is not peeled or if residual membrane persists.

Outcomes and prognosis

Many patients experience improved metamorphopsia and better or more stable central vision after PPV with membrane (and sometimes ILM) peeling.
Visual acuity gains are variable and depend on baseline vision, duration of symptoms, and integrity of the photoreceptor layers on OCT.
Cataract progression is a common later issue in eyes that undergo PPV, particularly if the natural lens is still in place.
Recurrence rates of ERM after removal are relatively low but not negligible, and higher recurrence is reported in cases without ILM peeling in some studies.
Overall, treatment decisions should balance symptom burden, patient expectations, potential benefits, and the risks of surgery.

Controversies and debates

Timing of surgery: Some clinicians advocate for early intervention in patients with noticeable distortion to prevent long-term photoreceptor damage, while others favor delaying surgery in favor of observation if vision remains functionally acceptable. The decision is usually individualized based on the patient’s symptoms, activity level, and OCT findings.
Role of ILM peeling: ILM peeling may reduce recurrence but adds surgical complexity and potential risk. The choice often depends on surgeon preference, intraoperative assessment, and patient-specific factors.
Use of dyes: Dyes assist membrane visualization but carry concerns about retinal toxicity. Clinicians weigh the diagnostic clarity gained against potential adverse effects.
Imaging-guided decision-making: Advances in OCT have improved the ability to quantify distortion and structural changes, but there is ongoing discussion about how best to translate imaging metrics into timing for surgery.
Access and cost considerations: Because surgery and imaging can be costly, some debates focus on healthcare resource allocation and ensuring appropriate indications for intervention, particularly in systems with budget constraints.

Prognosis after treatment

Most patients who undergo PPV with ERM peeling experience some improvement in distortion and, in many cases, in central vision. However, outcomes vary, and some individuals may have persistent metamorphopsia or require additional procedures (such as cataract surgery) later on. The prognosis improves when the duration of symptoms is shorter and when macular integrity is preserved preoperatively on OCT.