The prevalence of idiopathic epiretinal membranes (ERM) in people over 50 is estimated at 6 to 19%. Even though most cases show very few symptomats, they may induce alterations of the underlying retina and lead to visual impairment likely to greatly diminish quality of life in patients. Thanks to the ever-improving quality of vitreo-retinal surgery, ablation of these membranes is a frequent and safe procedure allowing a functional gain in the majority of cases. Given the increasing prevalence in the population concerned and the accelerated ageing of the lens after vitrectomy, cataract surgery is often associated with removal of the membrane. On the basis of a study in 142 patients, it was possible to identify clinical and morphological prognostic factors and to inclure them in a score to assess the chances of complete functional recovery at one year following the procedure . Age of the patient, the duration of symptoms, initial visual acuity and the quality of the junction between external and internal segments of photoreceptors in optic coherence tomography (OCT) appeared as significantly related to visual results. Using this score in a new prospective cohort would allow the investigators to make it a reliable and easy-to-use tool at the service of ophthalmologist surgeons and their patients and would provide scientific confirmation of the interest of earlier surgery in this disease. It would also allow the investigators to define in a validated and reproducible manner, a threshold for an ndication for ERM surgery, which is currently based on relatively subjective criteria mostly related to visual acuity.