Regional differences in foveal avascular zone morphology in cynomolgus macaques using a normative OCTA database

Abstract Cynomolgus macaques are widely used in preclinical ophthalmic research because of their close anatomical and physiological similarity to the human eye. However, the small cohort sizes typical of laboratory studies and the limited implementation of automated image analysis have restricted the availability of robust normative datasets. In particular, comprehensive reference values for foveal avascular zone (FAZ) measurements in laboratory cynomolgus monkeys remain scarce. To address this, an automated OCT/OCTA image-processing workflow was used to quantify FAZ morphology in healthy cynomolgus monkeys, including a deep learning-based OCT segmentation step followed by analysis of the corresponding OCTA data. The study also evaluated morphological variations as well as the influence of sex and geographical origin. The overall FAZ area measured 0.451 mm (range 0.132–0.820 mm 2 ), the perimeter 2.770 mm (range 1.569–3.795), aspect-ratio 0.959 mm (range 0.622–1.388), circularity 0.725 (range 0.517–0.847), solidity 0.944 mm (range 0.816–0.991 mm). Moreover, geographical origin significantly affects FAZ area and aspect-ratio. Establishing a normative FAZ reference database is essential for the accurate interpretation of structural and vascular changes in translational ocular research and provides a quantitative framework to distinguish physiological variability from treatment-related effects, thereby supporting safety assessment and efficacy evaluation in preclinical drug development.