The Impact of Deterministic Signal Loss on OCT Angiography Measurements.

Abstract

PurposeIn this study, we aimed at investigating the impact of deterministic signal loss on image quality and, thus, on optical coherence tomography angiography (OCTA) measurements performed by the RTVue-XR Avanti System.MethodsAbsorptive filters with different optical densities (ODs) were used to simulate signal loss in a controlled way in 30 eyes from 15 healthy subjects. Scan Quality (SQ), provided by the AngioVue software, was applied as a measure of image quality.ResultsAssessing the effect of decreased light transmittance on SQ values as well as that of attenuated image quality on OCTA parameters revealed a strong systematic dependence between these quantities. Attenuated image quality was associated with significantly decreased macular and peripapillary vessel density (VD) values, and we calculated a correction factor of 2.27% to 3.97% for a one-unit change in SQ for the different VD parameters.ConclusionsOur findings suggest that the influence of systematic changes in image quality on OCTA parameters needs to be considered during patient follow-up in order to make valid assessment of progression.Translational RelevanceFor accurate evaluation of longitudinal changes in OCTA parameters, equal scan quality or using a correction factor is suggested.