Changes in Aniseikonia in Patients with Idiopathic Epiretinal Membrane Treated with Pars Plana Vitrectomy: A Meta-Analysis

Objectives: This study aimed to assess longitudinal changes in aniseikonia following pars plana vitrectomy (PPV) in patients with idiopathic epiretinal membrane (ERM). Methods: This meta-analysis was conducted in accordance with the PRISMA guidelines. The PubMed, EMBASE, and Cochrane Library databases were searched from inception to March 2024 to identify studies evaluating aniseikonia outcomes after PPV for idiopathic ERM. Studies involving secondary ERM or those lacking aniseikonia assessments were excluded. Correlations between aniseikonia and best-corrected visual acuity (BCVA) and central macular thickness (CMT) were analyzed. Results: Ten studies comprising 456 eyes were included. PPV was associated with a statistically significant reduction in aniseikonia at all evaluated postoperative time points, including 1 month (−1.09%, p = 0.04), 3 months (−0.81%, p = 0.02), 6 months (−0.89%, p = 0.002), and 12 months (−1.13%, p < 0.001). Meta-analysis of outcomes at the final follow-up of each study also demonstrated a significant overall improvement in aniseikonia (−1.09%, p < 0.001). Subgroup analysis revealed a statistically significant improvement only in studies with long-term follow-up (≥12 months), whereas studies with short-term follow-up (≤6 months) did not show significant changes. No significant correlations were found between changes in aniseikonia and changes in BCVA, CMT, or other structural parameters. Conclusions: Aniseikonia showed a statistically significant but modest reduction after PPV for idiopathic ERM. However, the magnitude and consistency of improvement varied across studies, and its clinical significance remains uncertain. Improvements appeared gradual and more evident with longer follow-up, suggesting that longer-term follow-up may be necessary to adequately assess postoperative changes in aniseikonia.