REPEATABILITY OF AUTOMATED VESSEL DENSITY AND SUPERFICIAL AND DEEP FOVEAL AVASCULAR ZONE AREA MEASUREMENTS USING OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY: Diurnal Findings.

Abstract

To evaluate the repeatability of vessel density and superficial and deep foveal avascular zone measurements using optical coherence tomography angiography, and to specify a diurnal change range. Forty-six eyes of 25 healthy individuals were included. Optical coherence tomography angiography measurements were planned for three consecutive sessions, with 3 hours in between them. AngioVue software of the RTVue XR Avanti was used. Superficial and deep retinal layer vessel density values, including the whole retina, fovea, and each parafoveal zone, were obtained from the software. The intraclass correlation, coefficient of variation, and coefficient of repeatability were calculated for each parameter. The whole image intraclass correlation value was 0.81 for the superficial and 0.86 for the deep layer among the three consecutive sessions. The smallest real difference (coefficient of repeatability) value of whole image measurements was 7.72% for the superficial and 9.84% for the deep retinal layer. Foveal avascular zone area intraclass correlation value was 0.97 for the superficial and 0.83 for the deep retinal layer. The optical coherence tomography angiography analysis provides quantitative data about the retinal microvasculature, which could be used to distinguish between normal and pathology. Changes in superficial vessel density >8% and deep vessel density >10% may be considered as real clinical change rather than variation.