Macular Retinal Sensitivity and Microvasculature Changes before and after Vitrectomy in Idiopathic Macular Epiretinal Membrane with Classification

To observe retinal sensitivity (RS) and microvasculature changes in preoperative and postoperative idiopathic macular epiretinal membrane (iERM) with optical coherence tomography (OCT) classification by microperimetry (MP) and optical coherence tomography angiography (OCTA).In this retrospective study, 53 eyes of 53 patients affected with iERM were enrolled and 35 iERM eyes underwent pars plana vitrectomy associated with internal limiting membrane peeling. All iERM eyes were evaluated and graded by OCT. According to the thickness of the fovea relative to the surrounding macula from OCT radial line scans, we classified iERM into 3 grades. MP was used to measure RS of macular within 20° centered on the fovea and fixation stability (FS). OCTA was used to measure the superficial and deep capillary plexus (DCP) layers using 6 mm × 6 mm scans. Measurements were taken at the baseline visit and 3-month postoperation. Evaluated factors included: best corrected visual acuity, RS, FS, vessel density.Eyes with iERM had worse RS than control eyes (p < 0.0001), especially in higher grade iERM eyes. And higher grade iERM eyes had a marked increase foveal vessel density (FVD) (p < 0.0001) in superficial capillary plexus (SCP) and DCP, and a significant decrease parafoveal vessel density (Para VD) in DCP. After surgery, there was no difference in RS and FS than preoperation (p > 0.05), whether in grade 1 or 2 iERM eyes. However, in OCTA analyses, grade 1 iERM eyes had less whole vessel density (WVD) and perifoveal vessel density (Peri VD) in SCP, than preoperation (p < 0.05). And grade 1 iERM eyes had higher Para VD and Peri VD in DCP (p < 0.05), than preoperative OCTA results. Grade 2 iERM eyes had less WVD, FVD, and Peri VD in SCP, than preoperation (p < 0.05). After surgery, in grade 2 iERM eyes, there was a positive correlation between whole retinal sensitivity and WVD (p < 0.05) in SCP. And there were positive correlations between Para RS and Para VD (p < 0.05), Peri RS and Peri VD (p < 0.05) in SCP.Classification helps to reveal different changes in iERM eyes. Higher grade iERM eyes had worse RS and microvasculature changes. MP and OCTA play an important role in assessing iERM and help surgical decisions for patients with iERM.