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QUESTION

WHEN SHOULD I REFER A PATIENT WITH AN EPIRETINAL MEMBRANE AND WHAT IF THERE IS ASSOCIATED CYSTOID MACULAR EDEMA?

Gaurav K. Shah, MD
Daniel Connors, MD

An epiretinal membrane (ERM) is a disorder of the vitreomacular interface resulting in tangential tractional force on the retina leading to macular thickening and distortion. There is great variation in presentation with some patients visually asymptomatic and others with significant morbidity, including metamorphopsia and reduced vision. Pathologically, it is a result of fibrocellular proliferation on the innermost surface of the retina.^1,2

The prevalence of ERM varies based on the population being studied, with rates ranging from 2.2% to 18.5%, the incidence increasing with age.³ An ERM may be classified as primary or idiopathic, or secondary. A variety of common ocular conditions are known to be associated with ERM formation including diabetic retinopathy, retinal vein occlusion, history of retinal break or detachment, or trauma. While the exact cause of an idiopathic ERM is inherently unclear, it is believed to be due to anomalous posterior vitreous detachment.¹ Anomalous posterior vitreous detachment is the result of vitreous liquefaction occurring faster than the weakening of vitreoretinal adhesion, resulting in tractional forces on the retina. This traction is proinflammatory and causes the release of a variety of cytokines resulting in fibrocellular proliferation¹ (Figure 27-1). When evaluating a patient with an ERM, it is important to keep the etiologies of a secondary ERM in mind. Patients should specifically be evaluated for the presence of retinal vascular disease, uveitis, or an occult retinal break.

ERMs are often asymptomatic in the early stages, and the majority of these membranes remain stable after an initial period of growth. Progression, however, may lead to significant visual impairment, metamorphopsia, macropsia, diplopia, and even aniseikonia. It is especially important to ask these patients about symptoms of visual distortion that can occur in the setting of normal visual acuity. In many cases, Snellen visual acuity may not be consistent with the patient’s symptomatic complaints, and this may be more evident in those with professions that demand high visual quality (eg, pilots, physicians, nurses, engineers).

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