Automated Measurement of the Foveal Avascular Zone in Swept-Source Optical Coherence Tomography Angiography Images

Abstract

Purpose

The purpose of this study was to evaluate automated measurement of the foveal avascular zone (FAZ) area using the Kanno-Saitama macro (KSM) software in Image J with swept-source optical coherence tomography angiography (SS-OCTA) images.

Methods

In this cross-sectional study, one photographer scanned the macular area (3 × 3 mm) of healthy volunteers twice on the same day, at the same time. The FAZ area was measured from the en face image of the superficial retinal layer by two masked examiners, using the KSM and the Advanced Retina Imaging (ARI)-network method in Carl Zeiss online analysis. Intra- and interscan reproducibility and FAZ area were compared among the methods.

Results

Forty eyes of 22 healthy volunteers were included in the analysis. The mean ± SD age of the subjects was 34.6 ± 12.4 years. Intra- and interscan intraclass coefficients ranged from 0.997 to 1.000 and 0.989 to 0.995, respectively. The mean FAZ area was 0.264 ± 0.08 mm ² by the KSM, 0.245 ± 0.08 mm ² by the ARI, and 0.281 ± 0.09 mm ² by the manual method. The mean difference between the KSM and manual methods was 0.015 mm ², which was significantly smaller than the mean difference between the ARI and manual methods (0.034 mm ²; P < 0.001).

Conclusions

Automated determination of the FAZ area is feasible and yields results comparable to those obtained by manual measurement. The FAZ area measured with the KSM program is less user dependent and could potentially contribute to our understanding of the pathophysiology of various retinal diseases, particularly underlying vascular diseases.

Translational Relevance

This study demonstrates a novel automated determination of the FAZ area using the Image J macro program in SS-OCTA images. This program was feasible and yields results comparable to those obtained by manual measurement.