Measurement of Foveal Avascular Zone Dimensions and its Reliability in Healthy Eyes Using Optical Coherence Tomography Angiography

Abstract

Purpose: To measure foveal avascular zone (FAZ) dimensions in healthy eyes using optical coherence tomography angiography (OCTA) and calculate interobserver variability.

Design: Reliability analysis.

Methods: Thirty-four eyes of 17 healthy subjects underwent OCTA at the Retina Service of Wills Eye Hospital. Two masked graders performed measurements of FAZ dimensions including area, perimeter, and maximum horizontal and vertical diameters using ImageJ. Intraclass correlation coefficient (ICC) between graders was calculated.

Results: Mean area (mm(2)), perimeter (mm), and maximum horizontal and vertical diameters (mm) were 0.27 ± 0.101, 2.21 ± 0.451, 0.59 ± 0.126, and 0.56 ± 0.118, respectively, at the superficial and 0.34 ± 0.116, 2.50 ± 0.462, 0.69 ± 0.123, and 0.63 ± 0.110 at the deep network. Interobserver agreement was high for all superficial FAZ measurements (ICC ≥0.90) but did not meet the lowest acceptable grader agreement for the deep vascular network (ICC <0.85). Fellow eyes had statistically similar values (P > .05).

Conclusion: Manual measurement of FAZ dimensions using OCTA is a noninvasive and reliable method for quantifying FAZ at the superficial vascular network. Assessing FAZ alterations in the deep vascular network may be subject to greater interobserver variability.