Vitrectomy with or without internal limiting membrane peeling for idiopathic epiretinal membrane: A meta-analysis

Abstract

Background: Studies on vitrectomy with and without internal limiting membrane (ILM) peeling for idiopathic epiretinal membrane (ERM) have yielded uncertain results regarding clinical outcomes and recurrence rates.

Objective: To compare the clinical outcomes of vitrectomy with and without ILM peeling for idiopathic ERM.

Methods: Databases, including PubMed, Embase, Cochrane, Web of Science, Google Scholar, CNKI databases, FDA.gov, and ClinicalTrials.gov, published until July 2016, were searched to identify studies comparing the clinical outcomes following vitrectomy with ERM and ILM peeling and with only ERM peeling, for treating idiopathic ERM. Studies with sufficient data were selected. Pooled results were expressed as mean differences (MDs) and risk ratios (RRs) with corresponding 95% confidence intervals (CI) for vitrectomy with and without ILM peeling with regard to postoperative best corrected visual acuity (BCVA), central retinal thickness (CRT), and ERM recurrence rate.

Results: Eleven retrospective studies and one randomized controlled trial involving 756 eyes were identified. This demonstrated that the postoperative BCVA within 12 months was significantly better in the non-ILM peeling group (MD = 0.04, 95% CI: 0.00 to 0.08; P = 0.0460), but that the patients in the ILM peeling group had significantly better postoperative BCVA after 18 months (MD = -0.13, 95% CI: -0.23 to -0.04; P = 0.0049) than did those in the non-ILM peeling group. The non-ILM peeling group exhibited a higher reduction in postoperative CRT (MD = 51.55, 95% CI:-84.23 to -18.88; P = 0.0020) and a higher recurrence rate of ERM (RR = 0.34, 95% CI:0.16 to 0.72; P = 0.0048) than did the ILM peeling group. However, the improvement rates of BCVA (RR = 1.03, 95% CI:0.72 to 1.47; P = 0.8802) and postoperative CRTs (MD = 18.15, 95% CI:-2.29 to 38.60; P = 0.0818) were similar between the two groups.

Conclusions: Vitrectomy with ILM peeling results in better visual improvement in long-term follow-ups and lower ERM recurrence rates, and vitrectomy with only ERM peeling is more efficacious in reduction of CRT than is vitrectomy with ILM peeling.

Fig 1. Flow diagram of the process of identifying eligible studies.

Fig 2. Main results from the meta-analysis of vitrectomy with epiretinal membrane (ERM) and ILM peeling or with only ERM peeling in idiopathic ERM.

(A) Best-corrected visual acuity (BCVA) <12 months follow-up duration after surgery; vitrectomy with only ERM peeling yielded significantly better results; (B) BCVA >18 months follow-up duration after surgery; vitrectomy with ERM+ILM peeling yielded significantly better results; (C) rate of improvement in visual acuity, defined as ≥2 Snellen lines at the end of follow-up; the difference between the two groups was nonsignificant (D) ERM recurrence rate; was significantly lower in the ERM + ILM peeling group than in the ERM peeling only group (E) central retinal thickness (CRT) at the end of follow-up; the difference between the two groups was nonsignificant; (F) CRT reduction at the end of follow-up; CRT reduction was significantly higher in the ERM peeling group than in the ERM+ ILM peeling group.

Fig 3. Trial Sequential Analysis (TSA) of the ERM recurrence rate outcome in this meta-analysis.

TSA is a methodology that includes a sample size calculation for a meta-analysis with the threshold of statistical significance. The detailed settings of this TSA were shown as follows: Significance level = 0.05; Power = 0.80; incidence of control = 2.3; relative risk reduction = 30%; I² = 0%. Finally, the number of required samples is 1263 but this meta-analysis collected only 674 samples.