Epiretinal Membrane of Combined Hamartoma of Retina and Retinal Pigment Epithelium Versus Idiopathic Epiretinal Membrane

Purpose: To evaluate the postoperative changes in macular vessel density and the multifocal electroretinogram (mfERG) in the epiretinal membrane (ERM) of a combined hamartoma of the retina and retinal pigment epithelium (CHRRPE). And we compared these results with those of idiopathic ERM.Method: We retrospectively reviewed the records of 15 patients (15 eyes) with an epiretinal membrane of a CHRRPE, and 21 patients (21 eyes) with idiopathic ERM who were treated with pars plana vitrectomy and removal of the ERM. The best corrected visual acuity, central macula thickness, foveal and perifoveal vessel density, foveal avascular zone (FAZ), and mfERG rings 1 and 2 P1 amplitudes were analyzed before and 6 months after ERM removal.Results: The average macular vessel density in the CHRRPE with ERM was reduced (p = 0.047) compared to an idiopathic epiretinal membrane, but the central foveal vessel density was significantly increased (p = 0.003). In CHRRPE, the preoperative FAZ was significantly reduced, and while it increased significantly 6 months postoperatively. After removing the ERM, the P1 amplitude increased significantly on mfERG, but there was no significant difference compared to the idiopathic ERM.Conclusions: The macular mean superficial capillary plexus (SCP) vascular density was reduced in CHRRPE and the foveal SCP vascular density and FAZ were increased. Considering the increased size of the FAZ area after surgery, physical removal of the ERM affected the structural recovery of the fovea, but resulted in no significant improvement of the macular superficial microvascular system.