Retinal Tectonics after Macular Pucker Surgery: Thickness Changes and En-Face Displacement Recovery

Purpose: To study visual function, retinal layer thickness changes and tangential displacement after Pars Plana Vitrectomy (PPV) for EpiRetinal Membrane (ERM). Methods: Retrospective series of patients undergoing PPV for ERM, with 6-month follow-up including best-corrected visual acuity (BCVA), Optical Coherence Tomography (OCT), M-charts, ERM grading, and InfraRed fundus photo at time 0 (T0, pre-op) at month 1 (T1), 3 (T3), 6 (T6) post-op (±1 week). Retinal layer thickness and tangential (en-face) retinal displacement between successive times for the entire retinal surface and the central horizontal and vertical meridian were also measured. En-face displacement was calculated as optical flow of consecutive images. Results: Average BCVA improved from 0.28±0.08 logMAR at T0 to 0.16±0.25 at T6 (p=0.05), BCVA improvement correlated with BVCA at T0 (p<0.001). Vertical metamorphopsia decreased from 1.33°±0.70° at T0 to 0.82°±0.69° at T6 (p<0.05). Foveal thickness reduced from 453±53µm at T0 to 359±31µm at T6 (p<0.05) and reduction correlated with BCVA improvement (p<0.05). Foveal layers decreased (p<0.05) in all cases. Mean en-face deformation was 155.82±50.17µm and mostly occurred in the first month: T0-T1 displacement was 83.59±30.28µm, T1-T3 was 36.28±14.45µm, while T3-T6 was 39.11±22.79µm (p<0.001) on average. Peri-foveal and parafoveal deformation correlated with OCT foveal thickness reduction at all time intervals (1, 3, 6 months: p<0.01). Conclusion: ERM peeling affects all retinal layer thickness and results in new force balance across the entire retina and tangential displacement. Both en-face and in-depth changes correlate with visual function.