Abstract
PURPOSE: Several studies show that media opacity reduces vessel density (VD) measured by image processing algorithms of optical coherence tomography angiography (OCTA). However, different models of OCTA designed their own algorithms and computational methods, which may have different effects of opacity on VD. This study is aimed to investigate the impact of a simulated model of media opacity on quantitative measurement of two OCTA devices. METHODS: A spectral-domain based OCTA (Cirrus 5000; Carl Zeiss Meditec) and a swept-source based OCTA (Triton DRI-OCT, Topcon Inc.) were used to image retinal microvasculature at the macula using 3 × 3 mm scanning protocol from 22 eyes of 22 healthy subjects. Media opacity was simulated with neutral-density filters (optical density (OD)(λ=840nm) ranges 0.10-0.48 in Cirrus; OD(λ=1050nm) ranges 0.15-0.51 in Triton). The filters were placed in front of each study eye, and signal strength (SS) or signal strength intensity (SSI) was recorded during imaging. The parafoveal VD of superficial capillary plexus was then measured using the built-in software from the two devices. The correlations among OD, SS/SSI, and VD were analyzed. RESULTS: Increased OD was significantly correlated with decreased SS and SSI (r(s) = -0.576 and -0.922, respectively, both P < 0.001) in Cirrus and Triton, respectively. Although increased OD was significantly correlated with decreased VD in Cirrus (r(s) = -0.539, P < 0.001), there was no significant correlation between OD with VD in Triton (r(s) = -0.143, P = 0.137). CONCLUSIONS: The effect of media opacity on quantitative measurement of VD is different between different Cirrus and Triton OCTA devices. TRANSLATIONAL RELEVANCE: This study demonstrates that the effect of media opacity on VD measurement is different among different OCTA devices, suggesting that caution must be taken when interpreting VD measurement on OCTA, particularly among individuals with media opacity.