Volumetric High Resolution Optical Coherence Tomography: Findings In Vitreomacular Traction Before And Following Surgery

Abstract

Purpose: : To investigate the morphology of retinal layers and vitreoretinal interface by volumetric high resolution optical coherence tomography (HR–OCT) before and following peeling of epiretinal membranes.

Methods: : Three dimensional (3D) retinal imaging is performed using a second generation frequency domain HR–OCT system with a high axial resolution of 6 µm and up to 20kA–scans/second resulting in 256x256x1024 or 128x512x1024 voxels per volume. Raster scanning of an 5.8 mm by 5.8 mm field at 2 mm depth was performed to cover the macular region in full detail. Tomograms were correlated with conventional radial scanning covering only 6 scans and using extrapolation for missing sites. Twenty eyes of 20 patients with vitreomacular tractions due to epiretinal membranes were evaluated preoperatively and continuously at 1 and 4 days, 1 and 3 months postoperatively using HR–OCT retinal imaging. Visual acuity and fundus–photography were recorded at each visit.

Results: : High speed frequency–domain HR–OCT imaging enables unprecedented in–vivo 3D identification and dynamics of epiretinal traction. Epiretinal membranes are clearly delineated in the en face view and the distribution of traction forces throughout the intraretinal layers is identified down to the level of the retinal pigment epithelium. The morphology of the vitreomacular interface seen by OCT was in excellent agreement with clinical fundus examination techniques, but in addition crossectional tomograms included the intraretinal pathology. Volumetric HR–OCT was markedly superior to conventional time–domain OCT mapping. For follow–up postoperatively, a substantial release in traction was already documented at days 1 and 4.

Conclusions: : Volumetric HR–OCT provides highly detailed images of vitreomacular pathology. Morphological alterations including the epiretinal membrane as well as its effect on the outer and inner retinal structures are identified realistically and at all locations. Distinct changes after surgery with release of the traction forces and lack of iatrogenic damaged can be tightly evaluated in three dimensions. Identification of major traction paths allows improved surgical performance.

Keywords: imaging/image analysis: clinical • retina • macula/fovea