Influence of Removing the Large Retinal Vessels-related Effect on Peripapillary Vessel Density Progression Analysis in Glaucoma.

PURPOSE: To investigate the usefulness of removing the large vessel-related information from peripapillary optical coherence tomography angiography progression analysis. Peripapillary vessel density (VD) image series which had shown no progression with an earlier software version that did not separate capillary and large vessel-related effects were reevaluated for selective peripapillary capillary VD progression.
MATERIALS AND METHODS: Prospective retinal nerve fiber layer thickness and peripapillary VD measurements were made using the Angiovue/RTvue-XR OCT on 1 eye of 9 normal, 20 under treatment ocular hypertensive, and 24 under treatment open-angle glaucoma patients at 6-month intervals for 2 years (5 visits). In the current investigation the previously analyzed images were reanalyzed. Linear regression analysis for capillary VD progression in the radial peripapillary capillaries layer of the superior and inferior peripapillary hemifields, respectively, was made using the instrument's new software (version 2017.1, Phase 7 update).
RESULTS: A statistically significant negative capillary VD slope was found in 4 glaucoma eyes. Two eyes progressed in both hemifields, and 2 eyes in 1 hemifield. The rate of statistically significant progression ranged between -1.3% and-3.2% per year. In 2 eyes the spatially corresponding hemifield retinal nerve fiber layer thickness progression was also significant (-1.4 μm/y and -1.8 μm/y). No normal and ocular hypertensive eyes showed significant capillary VD progression.
CONCLUSIONS: In this 2-year prospective study no eye showed progression for peripapillary VD when all vessel-related information was used. In contrast, software-provided removal of the large retinal vessels-related information resulted in detection of significant capillary VD progression in 17% of the glaucoma eyes.