IMPORTANCE Vascular factors may have important roles in the pathophysiology of glaucoma. A practical method for the clinical evaluation of ocular perfusion is needed to improve glaucoma management.OBJECTIVE To detect peripapillary retinal perfusion in glaucomatous eyes compared with normal eyes using optical coherence tomography (OCT) angiography.

This article provides an overview of advanced image processing for three dimensional (3D) optical coherence tomographic (OCT) angiography of macular diseases, including age-related macular degeneration (AMD) and diabetic retinopathy (DR). A fast automated retinal layers segmentation algorithm using directional graph search was introduced to separates 3D flow data into different layers in the presence of pathologies. Intelligent manual correction methods are also systematically addressed which can be done rapidly on a single frame and then automatically propagated to full 3D volume with accuracy better than 1 pixel. Methods to visualize and analyze the abnormalities including retinal and choroidal neovascularization, retinal ischemia, and macular edema were presented to facilitate the clinical use of OCT angiography.

Optical coherence tomography angiography with SSADA was able to detect a decrease in peripapillary retinal blood flow in response to hyperoxia. The response was larger than the variability of baseline measurements. The magnitude of an individual's hyperoxic response was highly variable between days. Thus, reliable assessment may require averaging multiple measurements.

Abstract:We propose a novel automated volumetric segmentation method to detect and quantify retinal fluid on optical coherence tomography (OCT). The fuzzy level set method was introduced for identifying the boundaries of fluid filled regions on B-scans (x and y-axes) and C-scans (z-axis). The boundaries identified from three types of scans were combined to generate a comprehensive volumetric segmentation of retinal fluid. Then, artefactual fluid regions were removed using morphological characteristics and by identifying vascular shadowing with OCT angiography obtained from the same scan. The accuracy of retinal fluid detection and quantification was evaluated on 10 eyes with diabetic macular edema. Automated segmentation had good agreement with manual segmentation qualitatively and quantitatively. The fluid map can be integrated with OCT angiogram for intuitive clinical evaluation.

Purpose Use projection-resolved OCT angiography to investigate the autoregulatory response in the 3 parafoveal retinal plexuses under hyperoxia. Design Prospective cohort study. Participants Nine eyes from 9 healthy participants. Methods One eye from each participant was scanned using a commercial spectral-domain OCT system. Two repeated macular scans (3 × 3 mm2) were acquired at baseline and during oxygen breathing. The split-spectrum amplitude-decorrelation algorithm was used to detect blood flow. The projection-resolved algorithm was used to suppress projection artifacts and resolve blood flow in 3 distinct parafoveal plexuses. The Wilcoxon signed-rank test was used to compare baseline and hyperoxic parameters. The coefficient of variation, intraclass correlation coefficient, and pooled standard deviation were used to assess the reliability of OCT angiography measurements. Main Outcome Measures Flow index and vessel density were calculated from the en face angiograms of each of the 3 plexuses, as well as from the all-plexus inner retinal slab. Results Hyperoxia induced significant reduction in the flow index (−11%) and vessel density (−7.8%) of only the deep capillary plexus (P < 0.001) and in the flow index of the all-plexus slab (P = 0.015). The flow index also decreased in the intermediate capillary plexus and the superficial vascular complex, but these changes were small and not statistically significant. The projection-resolved OCT angiography showed good within-session baseline repeatability (coefficient of variation, 0.8%–5.2%; intraclass correlation coefficient, 0.93–0.98) in all parameters. Relatively large between-day response reproducibility was observed (pooled standard deviation, 1.7%–9.4%). Conclusions Projection-resolved OCT angiography was able to show that the retinal autoregulatory response to hyperoxia affects only the deep capillary plexus, but not the intermediate capillary plexus or superficial vascular complex.