Internal Limiting Membrane Peeling During Idiopathic Epiretinal Membrane Removal

Epiretinal membranes (ERMs) are proliferations of fibrocellular tissue on the retinal surface. The manifestations of ERMs range from visually insignificant thin films to thick membranes that can create retinal corrugations and folds, leading to decreased visual acuity, metamorphopsia, and monocular diplopia. Epiretinal membranes and organized hyaloid membranes can occur in various pathologic states, such as proliferative diabetic retinopathy, proliferative vitreoretinopathy, uveitis, pediatric vitreoretinopathies, perisilicone oil proliferation, and endophthalmitis. However, most cases of ERM formation are idiopathic, with the risk of ERM development increasing with age. The ERM formation is a relatively common phenomenon, as studies have shown that 2% of patients older than 50 years and 20% older than 75 years have some degree of ERM present. Although the vast majority of these cases are visually insignificant, a small percentage may prompt intervention. The pathogenesis of ERM formation is unclear, but it is known to be associated with the development of posterior vitreous detachment. It is thought that when the posterior hyaloid separates from the retinal surface, the glial cell processes undergo hypertrophy and the extracellular matrix is able to grow on the internal limiting membrane (ILM) surface. Epiretinal membranes can be diagnosed by the presence of a reflective sheen visualized on dilated fundus examination, oftentimes associated with distortion of the underlying retina and retinal vasculature. Optical coherence tomography (OCT) is an important adjunctive imaging tool that can be used to diagnose and monitor the progression of ERMs. Most cases of ERM remain stable or progress slowly. In very rare cases, they have been shown to separate spontaneously from the retinal surface. However, in the remaining cases, vitrectomy with mechanical peeling of the ERM has been the method of choice over the past several decades for removing these membranes. The removal of submillimeter tissue without inducing damage to the underlying retina makes ERM peeling arguably the most microscopic of surgeries in all of medicine. Despite this, advances in instrumentation and dyes to aid in visualization of the membranes have made ERM peeling one of the most commonly performed surgeries for the vitreoretinal surgeon. Numerous studies report good visual and anatomic outcomes with vitrectomy and ERM peeling, with improved vision in 70% to 90% of patients, with a mean of 2 or more Snellen lines of improvement, and reduced metamorphopsia. However, 1 or 2 patients of 10 will experience ERM reformation after vitrectomy with ERM removal. Recurrent ERMs are likely due to reproliferation stimulated by remnants of cortical vitreous on the retinal surface or incomplete ERM removal. Histologic studies have shown that ILM fragments may be present on the ERM after surgical removal. The ILM is not a true basement membrane but is created by fusion of the foot processes of the glia-like Müller cells. In fact, studies have shown that the more ILM that has been removed in conjunction with the ERM the better the visual outcomes. These observations lead to the theory that concurrent ILM removal, incidental or intentional, may improve outcomes by assuring more complete ERM removal, thereby maximizing surgical outcomes and possibly preventing the reformation of ERMs. In this review, we aim to summarize the pros and cons of ILM peeling during ERM surgery based on the existing literature.