Comparison of Peripapillary OCT Angiography Vessel Density and Retinal Nerve Fiber Layer Thickness Measurements for Their Ability to Detect Progression in Glaucoma

Purpose:The aim of this study was to investigate the applicability of peripapillary optical coherence tomography angiography angioflow vessel density measurements in the retinal nerve fiber layer for the detection of glaucomatous progression and to compare its performance with that of retinal nerve fiber layer thickness (RNFLT) measurements.Methods:Prospective RNFLT and vessel density measurements with the same Angiovue/RTVue-XR instrument were made immediately one after another on 1 eye of 9 normal eyes, 20 under treatment ocular hypertension eyes, and 24 under treatment open angle glaucoma eyes at 6-month intervals for 2 years (5 visits for all eyes). High image quality (signal strength index 50 to 91) was obtained for all measurements. No surgery was performed on any study eye during the study period. The normal and OHT cases were combined for comparison with the glaucoma group.Results:A statistically significant negative RNFLT slope was found in 16 eyes, whereas no eye had a significant negative vessel density slope (P<0.0001). The relative RNFLT and vessel density slopes were significantly different in the combined normal and OHT group, the glaucoma group, and the total population, respectively (P<0.0001). For the same groups, the relative residual SD was significantly higher for vessel density than for RNFLT measurements (P0.0019). The relative residual SD of RNFLT measurements was higher in the glaucoma group than in the combined normal and OHT group (P=0.0056), whereas the relative residual SD of vessel density measurements did not differ between the groups (P=0.3032).Conclusion:In this 2-year prospective study, peripapillary vessel density measurement did not support the detection of glaucomatous progression.