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

Abstract

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.

Tangential Retinal Displacement Increases After Macular Pucker Surgery: An Apparent Nonsense

“…The present study used the same method previously described as an objective measure of retinal tangential dislocation after ERM peeling 6 and extended its application to the preoperative period, immediately after the diagnosis of ERM and well before a decision for surgery was made. Although the exact time of onset of ERMs is virtually impossible to define, including a lengthy preoperative follow-up allowed us to study a prolonged period of the disease, including the changes leading to surgery.…”

“…En face dislocation was evaluated by measuring the displacement occurring between pairs of successive infrared 9 × 9-mm 2 -wide images acquired as spectral-domain optical coherence tomography (Spectralis HRA-OCT, version 1.5.12.0; Heidelberg Engineering, Heidelberg, Germany) by means of an optical flow algorithm described elsewhere. 6 The present study analyzed the displacements occurring during the preoperative period (T E − T 0 ), the postoperative period (T 0 − T L ), and the entire course of observation (T E − T L ).…”

“…4,5 We recently described a novel image analysis technique aimed at calculating the map of the displacements in consecutive retinal images and used it to study the postoperative en face retinal distortion after ERM peeling. 6 The present study aims at reporting retinal displacement and vision function throughout the course of disease, starting well before surgery was deemed necessary, shortly after the diagnosis of ERM was made, and after surgery with a lengthy postoperative follow-up. The purpose is to observe if and to what extent the surgical removal of ERMs reestablishes the previous premorbid ultrastructural anatomy or rather it results in a new and different configuration, shaped by the balance of forces established after the surgery.…”

“…We recently described a novel image analysis technique aimed at calculating the map of the displacements in consecutive retinal images and used it to study the postoperative en face retinal distortion after ERM peeling. 6…”

Three-Dimensional Retinal Displacement Before and After Macular Pucker Surgery

“…1 Epiretinal membranes may cause profound alterations of both the inner and outer retina 2 resulting in macular pucker requiring pars plana vitrectomy (PPV) with membrane peeling if visual acuity is significantly impaired. 3 We recently calculated the tangential displacement of the retina (i.e., across the coronal plane), using a novel image analysis technique 4 on InfraRed (IR) images taken before and after macular pucker surgery and demonstrated that retinal coronal dislocation after surgery is indeed greater than before. We also found only an erratic association between coronal displacement, visual acuity, and metamorphopsia changes, in agreement with previous studies.…”