Rhombus deformation of retinal lateral displacement after epiretinal membrane removal revealed by diffeomorphic image registration.

Abstract

To establish an analysis method using diffeomorphic image registration and evaluate microvascular displacement through epiretinal membrane (ERM) removal. Medical records of eyes that underwent vitreous surgery for ERM were reviewed. Postoperative optical coherence tomography angiography (OCTA) image s were converted to the corresponding preoperative images according to a configured algorithm using diffeomorphism. Thirty-seven eyes with ERM were examined. Measured changes in the foveal avascular zone (FAZ) area showed a significant negative correlation with central foveal thickness (CFT). The average amplitude of microvascular displacement calculated for each pixel was 69±27 μm in the nasal area, which was relatively smaller than that in other areas. The vector map, which included both the amplitude and vector of microvasculature displacement, showed a unique vector flow pattern called the rhombus deformation sign in 17 eyes. Eyes with this deformation sign showed less surgery-induced changes in the FAZ area and CFT and a milder ERM stage than those without this sign. We calculated and visualized microvascular displacement using diffeomorphism. We found a unique pattern (rhombus deformation) of retinal lateral displacement through ERM removal, which was significantly associated with the severity of ERM.