Correlation Between Laser Speckle Flowgraphy and OCT-Derived Retinal and Choroidal Metrics in Healthy Human Eye

PURPOSE: To investigate the correlation between laser speckle flowgraphy (LSFG) signals and the quantitative metrics derived from optical coherence tomography (OCT) in normal eyes. METHODS: LSFG, OCT, and OCT angiography (OCTA) imaging were performed on normal participants using a custom-designed LSFG system and a commercial swept-source OCT system. Mean (PWM) and amplitude (PWA) of the LSFG pulse waveform were selected to quantify the LSFG signals. Retinal and choroidal maps were obtained using the standard 6 × 6 mm OCT and OCTA scans. Structural and vascular metrics maps, including thickness, vessel area density, vessel skeleton density, and vessel diameter index of the retina, and choroidal thickness (CT), choroidal vessel volume (CVV) and choroidal vessel index (CVI), were employed to quantify the retinal and choroidal properties. Correlation analysis was then performed between the LSFG, retinal, and choroidal metrics maps. RESULTS: Twelve healthy participants aged 23 to 36 years were enrolled in this study. The spatial distribution of the PWM and PWA values was highly correlated with that of the CT and CVV metrics. On average, Spearman correlation coefficients (ρ) were 0.80 and 0.78 (all P < 0.001) for the correlations between PWM and CT and CVV, respectively, and were 0.61 and 0.63 (all P < 0.05) for the correlations between PWA and CT and CVV, respectively. In comparison, both PWM and PWA were generally weak or not correlated with all the retinal metrics and CVI. CONCLUSIONS: LSFG signals were positively correlated with the choroidal thickness and vessel volume, suggesting choroidal blood flows dominate the LSFG signals at the area absent of large retinal vessels. TRANSLATIONAL RELEVANCE: This study illustrates the dominant source of the LSFG signals in the eye.