Purpose: To establish an objective and quantitative biomarker of metamorphopsia in epiretinal membranes (ERMs) and determine the optimal timing for ERM surgery.
Methods: Retrospectively, 172 eyes with ERM were reviewed. Retinal folds because of tangential traction by ERM were visualized by en-face optical coherence tomography. The maximum depth of retinal folds (MDRF) within the parafovea was quantified. Metamorphopsia was quantified by M-CHARTS. The change in the distance between the retinal vessels after ERM surgery and the preoperative total depth of retinal folds between the vessels were quantified using en-face optical coherence tomography and optical coherence tomography angiography.
Results: Significant correlations were observed between preoperative MDRF and M-CHARTS scores before and at 6 months after surgery (r = 0.617 and 0.460, respectively; P < 0.001) and change in the distance between the retinal vessels after ERM surgery and preoperative total depth of retinal folds between the vessels (r = 0.471; P = 0.013). The preoperative MDRF values at which M-CHARTS scores were 0.5 before and 6 months after the surgery were 69 µm and 118 µm, respectively.
Conclusion: The MDRF is an objective and quantitative biomarker of metamorphopsia in ERM. To maintain patients' quality of vision, ERM surgery may be performed when the preoperative MDRF ranges between 69 µm and 118 µm.