Visual outcomes of monocular idiopathic epiretinal membrane removal: a prospective follow-up study

Background: Surgical intervention for an idiopathic epiretinal membrane (iERM) could alleviate metamorphopsia or improve vision. We evaluated changes in vision in patients undergoing treatment for monocular iERMs during a 6-month period. We investigated the rate of posterior vitreous detachment (PVD) using optical coherence tomography (OCT) imaging in eyes with iERM and in normal fellow eyes. We also examined the intraoperative rate of PVD in iERM eyes following the administration of triamcinolone acetonide (TA). Methods: This prospective interventional case series recruited all eligible individuals with treatment-naive monocular iERM who were scheduled for pars plana vitrectomy (PPV) due to reduced best-corrected distance visual acuity (BCDVA) or metamorphopsia. OCT at baseline was used to determine the presence and stage of PVD in the eyes with iERM and the normal fellow eyes. Intraoperative TA-based PVD staging was performed for affected eyes. Results: Participants comprised 32 cases, with 32 eyes with iERM and 32 normal fellow eyes. The mean (standard deviation [SD]) age was 60.9 (9.7) years, and the majority were men (n = 18, 56.2%). The baseline mean (SD) of BCDVA in affected eyes was 0.50 (0.21) logarithm of the minimum angle of resolution (logMAR), which improved to 0.34 (0.20) logMAR at the 1-month visit, representing a significant mean difference of 0.15 (0.20) logMAR (P < 0.001). At the 6-months visit, the mean (SD) BCDVA had further improved to 0.26 (0.19) logMAR, representing a significant mean difference of 0.23 (0.26) logMAR (P < 0.001) from the baseline value. The mean (SD) visual improvement between the 1- and 6-months follow-ups was 0.07 (0.14) logMAR, which was statistically significantly (P < 0.05). The mean changes in BCDVA were more pronounced in patients aged < 60 years than in those aged ? 60 years. The proportion of eyes at each stage of PVD detected by preoperative OCT in eyes with iERM differed from that detected by intraoperative TA staining. By both methods, the stages advanced significantly with increasing age (both P < 0.001). Similarly, the proportion of eyes at each stage of PVD detected by preoperative OCT in the normal fellow eyes was also higher and advanced significantly with increasing age (P < 0.001). Conclusions: Continuous visual improvement is anticipated up to 6 months after surgery in eyes with iERM, and this improvement is likely to be more significant in younger individuals. The incidences of each PVD stage varies depending on the use of preoperative OCT or intraoperative TA in these cases. A higher rate of PVD observed in fellow eyes may suggest that PVD progresses through its stages simultaneously and without complications in normal eyes. Further studies are needed to validate our preliminary results and confirm these conclusions.