Retinal relaxation following membrane peeling: Effect on vision, central macular thickness, and vector analysis of motion

BACKGROUND: Epiretinal membranes (ERM) form as a result of an inward displacement of retinal structures. Removal of an ERM leads to the outward displacement of retinal vessels and visual improvement. PURPOSE: The aim of the study was to evaluate the direction and extent of displacement of retinal/superficial vascular structures after a membrane peeling procedure by means of image comparison and in selected cases, a vector analysis of displacement. METHODOLOGY: Scanning laser ophthalmoscope images of the retina of eyes undergoing ERM peeling were compared before and 6 months after surgery. Stratification was made between prominent and limited displacement, with assessment of visual acuity (VA), and central macular thickness (CMT). In three cases, using the optic nerve as reference, 50 landmarks were chosen within the posterior pole along large and small vascular structures allowing the construction of a vector map of displacement over 1 year. RESULTS: Nine eyes with prominent and six with limited displacement were assessed. Improvement in VA was similar for both groups, while CMT drop was greatest for the worst group. Vector analysis showed that most vascular movement occurs over the first 6 months, covers most of the posterior retina, is centered around distinct nodes, and may lead to several hundred micrometers of displacement. CONCLUSIONS: Superficial retinal relaxation has no direct implication on visual recovery. It originates in nodes of retinal contraction. Its extent can be significant, covering most of the posterior pole. RELEVANCE FOR PATIENTS: A better understanding of retinal relaxation following the peeling of ERM may help better understand when intervention is required and which part of the membrane is critical to surgical success.