Purpose: Primary surgery failure of macular holes causes poor visual acuity outcomes. Several studies indicate that small-medium idiopathic full-thickness macular holes (iFTMH) have consistent and high anatomical closure rates after vitrectomy and internal limiting membrane (ILM) peeling, regardless of iFTMH diameters. However, there is no systematic analysis examining the relationship between iFTMH diameters and anatomical closure rates. Methods: In this systematic review and meta-regression, we searched PubMed, Embase, and Web of Science databases on October 24th, 2022. We included studies regarding iFTMH, with ILM peeling/inverted flap technique, long-lasting gas tamponade, and face-down position after surgery. Univariable meta-regression with a restricted cubic spline model and component-plus- residual plot after covariables adjustment were used to explore non-linear association. Results: A total of 7257 participants from 19 randomized controlled trials and 49 observational studies were included in this meta-analysis. In ILM peeling group, every 100-mu m increment in diameter was associated with a 3.8 % (95 % confidence interval [CI], 1.8%-5.7 %, P < 0.001) relatively lower anatomical closure rate. Yet, among studies using the inverted flap technique, baseline iFTMH diameter was not associated with a lower anatomical closure rate (0.2 %, 95%CI,-4.2 %-4.5 %, P > 0.9). The restricted cubic spline model and component-plus-residual plot controlling for age, sex, and symptom duration prior to surgery showed no evident non-linearity in both surgical techniques . Conclusions: The iFTMH diameter is linear and inversely associated with the anatomical closure rate after the ILM peeling technique, but not with the inverted flap technique. The present study supports the use of advanced techniques, e.g., inverted flap technique, in small-medium iFTMH to improve anatomical closure rates.