Influence of internal limiting membrane peeling during idiopathic epiretinal membrane removal: a randomized controlled trial

In epiretinal membrane (ERM) surgery, the influence of internal limiting membrane (ILM) integrity after ERM removal is underexplored. This study investigated outcomes of idiopathic ERM surgery based on ILM condition following ERM removal and intentional peeling of residual ILM. In this prospective, randomized clinical trial, 102 patients underwent vitrectomy for idiopathic ERM. After ERM removal, ILM status was evaluated using indocyanine green staining. Patients with mostly removed ILM were allocated to group 1 (involuntary peeling), whereas those with partially removed or intact ILM were randomized 1:1 to active peeling (group 2) or non-peeling of residual ILM (group 3). Recurrence of ERM during 12-month follow-up occurred only in group 3 (36.1%), particularly when residual ILM involved the fovea. Best-corrected visual acuity, metamorphopsia, and aniseikonia did not differ among groups; however, group 3 showed significantly lower central macular thickness at all follow-ups (p < 0.05) and better macular contour restoration according to retinal thickness profiles. In patients whose residual ILM involved the fovea, non-peeling resulted in less severe vertical metamorphopsia when ERM did not recur. These findings suggest that residual ILM peeling decisions during ERM surgery should consider both anatomical and functional outcomes, as non-peeling favoring anatomical macular recovery but increasing recurrence risk.