Surgery for Idiopathic Epimacular Membrane: Morpho-Functional Outcomes Based on the Preoperative Macular Integrity of the Photoreceptoral Junction. A Prospective Pilot Study

Introduction: This study aimed to evaluate whether the preoperative integrity of the inner segment (IS) and outer segment (OS) photoreceptoral junction may influence the postoperative visual acuity, the macular morphology [assessed by spectral domain optical coherence tomography (SD-OCT)], and macular function (evaluated by multifocal electroretinogram, mfERG) in patients with idiopathic epimacular membrane (EMM) followed up for 6 months. Methods: In this observational prospective study, 18 patients with EMM (mean age 72.5 ± 6.87 years) were enrolled. They were divided into two groups according to the preoperative integrity of the SD-OCT IS/OS junction: the EMM-I group with an intact IS/OS junction (11 patients, mean age 72.75 ± 3.49 years, providing 11 eyes) and the EMM-D group with a disrupted IS/OS junction (7 patients, mean age 70.86 ± 10.79 years, providing 7 eyes). For each enrolled patient, visual acuity (VA), mfERG, and SD-OCT were assessed at baseline (preoperative) and after 1, 3, and 6 months of follow-up after surgical treatment for EMM (pars plana vitrectomy with EMM removal and internal limiting membrane peeling). Results: During the whole follow-up, VA was significantly increased in EMM-I eyes and unmodified in EMM-D eyes. In both groups, mfERG responses were not significantly different and not related to VA differences. In EMM-I eyes a significant reduction of central retinal thickness (CRT) was observed; however, it was not correlated with VA changes. In EMM-D eyes CTR was not significantly reduced, whereas macular volume was significantly reduced. These changes were significantly related to the corresponding differences in VA. Conclusions: Our results suggest that the preoperative evaluation of the integrity of the IS/OS junction is relevant for postoperative outcomes. The recovery in VA was higher in EMM-I eyes than in EMM-D eyes. Postoperative recovery was not associated with morphology of the outer retina (photoreceptor and outer nuclear layer) and the function of preganglionic elements.