What are the causes of Epiretinal Membrane (ERM)?

Causes of Epiretinal Membrane (ERM)

Epiretinal membranes are classified as either idiopathic (without clearly identifiable cause) or secondary to specific ocular conditions, with the majority being idiopathic and related to age-related posterior vitreous detachment. 1

Idiopathic ERM

The most common form of ERM is idiopathic, occurring without a clearly identifiable precipitating cause. 1

• Idiopathic ERMs develop through fibrocellular proliferation on the neurosensory retinal surface, comprising reactive cellular elements, vitreous structures, and fibrotic components 1
• The pathogenesis involves reactive wound healing with proliferation of either retinal pigment epithelial (RPE) cells and/or retinal glial cells 1
• These cells reach the retinal surface via defects in the internal limiting membrane or from the vitreous cavity through transdifferentiation 2

Key Risk Factors for Idiopathic ERM

• Increasing age is the single most consistent and important risk factor across all population studies 1, 2
• Female gender significantly confers higher risk based on systematic review of over 49,000 subjects 1
• Posterior vitreous detachment (PVD) is a major associated factor, as vitreous may remain adherent to the macula during PVD evolution 1, 3

Secondary ERM Causes

Secondary ERMs occur after specific retinal or ocular pathologies that trigger reactive cellular proliferation. 1

Retinal Structural Abnormalities

• Retinal breaks or tears 1
• Retinal detachments 1
• Retinal laser or cryotherapy treatment 1

Retinal Vascular Disease

• Diabetic retinopathy (including proliferative diabetic retinopathy) 1, 2
• Retinal vein occlusions 1

Inflammatory Conditions

• Uveitis 1
• Ocular inflammatory diseases 1

Surgical and Traumatic Causes

• Intraocular surgery (particularly cataract surgery) 1, 2
• Ocular trauma 1

Pathophysiologic Mechanism

The underlying mechanism involves reactive wound healing at the vitreomacular interface, regardless of whether the ERM is idiopathic or secondary. 1

• During PVD evolution, the posterior vitreous partially detaches but may remain attached within the macular region 1, 3
• Vitreous remains most firmly attached at three locations: the vitreous base, optic nerve head, and macula 1
• Abnormal adhesion at the macula during PVD creates conditions for cellular proliferation 1
• Myofibroblastic pre-retinal cells transdifferentiate from glial and RPE cells that migrate through internal limiting membrane defects 2

Clinical Pitfalls

A common misconception is that all ERMs require treatment; however, the majority remain relatively stable and do not require intervention. 1

• Distinguishing idiopathic from secondary ERM is critical, as secondary forms require addressing the underlying condition 1
• The presence of ERM does not automatically indicate need for surgery—symptoms (decreased visual acuity, metamorphopsia) drive treatment decisions 1, 4
• Bilateral ERMs occur in 20% to 35% of cases, requiring examination of both eyes 1