Morphological Characteristics of Normal Foveal Avascular Zone by Optical Coherence Tomography Angiography

Purpose. To provide quantitative measurements for the foveal avascular zone (FAZ) and to describe its morphological characteristics by optical coherence tomography angiography (OCT-A).Design. Cross-sectional observational case series.Methods. Healthy volunteers were recruited and evaluated using Triton-DRI SS-OCT Angiography. A 4.5 x 4.5 mm square was evaluated by OCT-A center around the fovea. Superficial and deep capillary plexus were identified, and different quantitative measurements were conducted along with categorization of the FAZ pattern.Results. Eighty-two eyes (41 volunteers) were evaluated. Mean age was 30.59 +/- 7.6 years (23-42 years). Mean subcentral retinal thickness was 200.1 +/- 5.66 um (192-210 um). The number of terminal vessels was variable (range, 8-11). Mean maximum terminal vessel-to-vessel intervening distance was 527.8 +/- 60.3 um (471-674 um). Mean minimum terminal vessel-to-vessel intervening distance was 296.7 +/- 45.8 um (233-373 um). Mean maximum horizontal diameter of FAZ (superficial) was 716.17 +/- 124.09 um, while mean maximum vertical diameter of FAZ (superficial) was 667.76 +/- 131.28 um. Mean maximum horizontal diameter of FAZ (deep) was 823.19 +/- 144.92 um, while mean maximum vertical diameter of FAZ (deep) was 794.03 +/- 150.28 um. OCT-A detected different FAZ patterns; horizontally oval configuration in 32 eyes (39%), rounded configuration in 24 eyes (29.3%), pentagon configuration in 14 eyes (17.1%), and vertically oval and nonspecific configuration in 6 eyes each (7.3%).Conclusion. OCT-A could efficiently provide both quantitative and qualitative assessment of normal FAZ; such characterizations were difficult by standard FAZ assessment procedures like FFA.