The foveal avascular zone area in healthy eyes measured by ocular coherence tomography angiography using a full spectrum probabilistic algorithm.

Purpose: Report the foveal avascular zone (FAZ) area imaged by OCT angiography (OCTA) using a full spectrum probabilistic algorithm in eyes of healthy individuals from Costa Rica without any ocular or systemic pathology.

Methods: Retrospective chart review of consecutive healthy patients that were evaluated from January 2018 to October 2018 that underwent OCTA of the macular area. The OCTA consisted of a 10° × 10° cube of 512 A scans separated by 6 µm each with an automated real time mode of 5. The FAZ area of the superficial vascular complex (SVC), the deep vascular complex (DVC), superficial vascular plexus (SVP), intermediate vascular plexus (IVP) and the deep vascular plexus (DVP) were measured manually by 2 different observers at 3 different times.

Results: A total of 234 eyes of 121 patients were included in this study. Mean age was 50 years (range, 15-89), 85 patients (70%) were female. Inter- and intra-observer agreements were excellent. The mean FAZ areas in the different layers were 0.258 ± 0.0035 mm for the SVC, 0.205 ± 0.01 mm for the DVC, 0.415 ± 0.01 mm for the SVP, 0.305 ± 0.01 mm for the ICP and 0.420 ± 0.01 mm for the DCP. The mean FAZ areas in most of the measured layers increased with age and decreased with CMT. Gender and spherical equivalence were not correlated with FAZ area.

Conclusion: Manual measurements of the FAZ imaged by OCT-A using a full spectrum probabilistic algorithm are widely reproducible both by the same observer and between observers. The FAZ increases with age and decreases with CMT in normal individuals.