PURPOSE:
To develop and evaluate an automated method to measure the foveal avascular zone (FAZ) area in healthy eyes on Heidelberg Spectralis Optical Coherence Tomography Angiography (HS-OCTA). This method is referred to as the modified Kanno-Saitama macro (mKSM).
METHODS:
This cross-sectional study included 29 eyes of 25 healthy volunteers who underwent HS-OCTA at the macular area twice at the same time. Regardless of the quality of the images, all of them were included. Macular data on the superficial vascular plexus, intermediate capillary plexus and deep capillary plexus were processed by mKSM. The FAZ area was measured twice automatically using the mKSM and twice manually by two independent examiners.
RESULTS:
Intrascan intraclass coefficient ranged from 0,948 to 0,993 for manual measurements and was 1 for mKSM method. Interscan intraclass coefficients ranged from 0,925 to 0,973 for manual measurements and from 0,770 to 0,902 for mKSM method. Despite that the difference between human examiners is smaller than between human examiners and mKSM according to Bland-Altman plots, the scatterplots show a strong correlation between human and automatic measurements. The best results are obtained in intermediate capillary plexus.
CONCLUSIONS:
Automated determination of the FAZ area in HS-OCTA is feasible and less human-dependent by mKSM even if the image is not perfectly centred or has artefacts. The mKSM processing could contribute to our understanding of the three vascular plexuses.
Factors influencing foveal avascular zone size in healthy eyes
