Clasificación de la MER

I will explain the classification of epiretinal membranes (ERM). Historically, ERM classification was based on clinical examination. In 1987, Gass first proposed a clinical classification with four levels of increasing severity. Many ophthalmologists used Gass's simplified two-level classification: cellophane macular reflex, which is the initial mild form, and a severe late form called preretinal macular fibrosis. Currently, clinical classification has lost relevance, and classifications based on optical coherence tomography (OCT) have become the standard. Classification of ERM with OCT Currently, optical coherence tomography (OCT) is the technique of choice for diagnosing ERM because it is much more sensitive and accurate than clinical examination alone. Several OCT-based classifications of ERM exist, and to date, there is no general consensus on which one to use. One of the most widely used today is the one proposed in 2017 by Govetto A, et al. Evaluating the foveal depression, the structure of the retinal layers, and proposing a new concept: ectopia of the inner foveal layers. Ectopia of the inner foveal layers. Ectopia in medicine means displacement. Here we see an OCT image with a normal retina and in the center the foveal depression, which is the area of ​​best vision. All the retinal layers are perfectly defined, and I have indicated the inner nuclear layer and the wider outer nuclear layer, which I have highlighted in blue. In this OCT image, we see an ERM that, when it contracts, widens the outer nuclear layer (hyporeflective) and displaces towards the surface of the foveal area along with all the inner layers of the retina. ERM 1: The membrane is thin, the foveal depression is visible, and the retinal layers are very well differentiated. ERM 2: There is no foveal depression. The retinal layers are well differentiated, but the outer nuclear layer is widened. MER 3: No foveal depression. The retinal layers are well-defined, but the inner foveal layers show continuous ectopia throughout the thickened central area. MER 4: Thick, opaque membrane. No foveal depression, the inner foveal layers are ectopic, and the retina is thickened with unstructured layers that are difficult to distinguish. In MER 1, 2, and 3, all retinal layers are clearly defined on OCT. Visual acuity progressively decreases from stage 1 to stage 4. Govetto A, et al. Soy J Oftalmol. March 2017; 175:99-113. The classification is simple, reliable, and reproducible. Foveal depression is only observed in stage 1 MER. Membrane traction eliminates the depression in stage 2, and progressively increases foveal thickness in stages 3 and 4. In stages 1, 2, and 3 MER, all retinal layers are clearly defined on OCT; they are only disrupted in stage 4 MER. Visual acuity progressively decreases from stage 1 to stage 4. Cystoid spaces appear in some membranes, and in the most advanced cases, folds appear in the inner retina, thickening the macula. Changes in the posterior part of the fovea: Contraction of the MER also produces changes in the outermost part of the central retina anterior to the RPE. This area is highly sensitive to MER traction via the Müller cells. On OCT, they present a continuous spectrum with three similar appearances: -the cotton ball sign, -acquired vitelliform lesions, or -foveolar detachment. Cotton ball sign. 65% of eyes with MERi present a highly reflective, rounded, and diffuse formation in the center of the fovea, called the "cotton ball sign," whose 100µm diameter is sometimes referred to as the "central branch." Bonafonte Ophthalmology Center Eye Surgery and Diseases Pasaje Méndez Vigo 6, 08009 Barcelona, ​​Spain Spain Tel: +34 934 870 015 Visit our website: www.centrodeoftalmologiabonafonte.com Email: [email protected] Instagram:   / centrodeoftalmologiabonafonte   Facebook:   / centrodeoftalmologiabonafonte