Purpose To investigate the repeatability, interocular correlation and agreement of quantitative swept-source optical coherence tomography angiography (SS-OCTA) metrics in healthy subjects.
Methods Thirty-three healthy normal subjects were enrolled. The macula was scanned four times by an SS-OCTA system using the 3 mm×3 mm mode. The superficial capillary map images were analysed using a MATLAB program. A series of parameters were measured: foveal avascular zone (FAZ) area, FAZ perimeter, FAZ circularity, parafoveal vessel density, fractal dimension and vessel diameter index (VDI). The repeatability of four scans was determined by intraclass correlation coefficient (ICC). Then the averaged results were analysed for intereye difference, correlation and agreement using paired t-test, Pearson’s correlation coefficient (r), ICC and Bland-Altman plot.
Results The repeatability assessment of the macular metrics exported high ICC values (ranged from 0.853 to 0.996). There is no statistically significant difference in the OCTA metrics between the two eyes. FAZ area (ICC=0.961, r=0.929) and FAZ perimeter (ICC=0.884, r=0.802) showed excellent binocular correlation. Fractal dimension (ICC=0.732, r=0.578) and VDI (ICC=0.707, r=0.547) showed moderate binocular correlation, while parafoveal vessel density had poor binocular correlation. Bland-Altman plots showed the range of agreement was from −0.0763 to 0.0954 mm2 for FAZ area and from −0.0491 to 0.1136 for parafoveal vessel density.
Conclusions The macular metrics obtained using SS-OCTA showed excellent repeatability in healthy subjects. We showed high intereye correlation in FAZ area and perimeter, moderate correlation in fractal dimension and VDI, while vessel density had poor correlation in normal healthy subjects.
- Optical coherence tomography angiography
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Funding This study was supported by the National Nature Science Foundation of China (30901646 and 81170853), Yangfan Project and Tezhi Project of Guangdong Province.
Competing interests None declared.
Ethics approval The study adhered to the tenets of the Declaration of Helsinki and was approved by the Institutional Review Board of Joint Shantou International Eye Center of Shantou University and The Chinese University of Hong Kong.
Provenance and peer review Not commissioned; externally peer reviewed.
Patient consent Obtained.
Contributors DF: conducted the study and drafted the manuscript. FYT: analysed the images. HH: recruited the subjects. CYC: analysed the images and revised the manuscript. HC: designed the study and revised the manuscript.
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