Abstract
Purpose :
Optical coherence tomography angiography (OCTA) is a novel non-invasive technique for visualizing of the retinal and choroidal microvascular system. Non-human primates (NHP) are widely used in preclinical ocular research due to their anatomical and genetic similarities shared with human eyes. The purpose of this study was to characterize the OCTA feature and establish standardized methods for evaluating retinal vascular complexes in NHP.
Methods :
Nine eyes from six healthy adult cynomolgus monkeys were included in this study. The OCTA images (20°×20°,512 A-scans/B-scan and 512 B-scans/volume) were obtained from the macula (fovea-centered) and peripapillary (optic nerve head-centered) region using the OCTA module of Heidelberg Spectralis HRA+OCT. After segmentation into different layers, images were processed using Fiji software, and quantitative parameters of the retinal vasculature were evaluated.
Results :
In cynomolgus monkeys, retinal and choroidal microvasculature can be visualized using the OCTA system. The superficial vascular complex (SVC, ILM to IPL) and deep vascular complex (DVC, IPL to OPL) can be distinguished in the retinal. The superficial capillary plexus (SCP) appears as a fine capillary network with an intense signal. Deep capillary plexus (DCP) presents a dense capillary network developing all around the perifoveal area. The corresponding B scan image displays hyperreflective dots stratified in two layers. In the choroidal layer, choriocapillaris exhibit numerous tiny hyper- or hypo-intense dots in a homogeneous pattern, while large choroidal vessels exhibit distinct hypo-intense linear structures in OCTA images. At the level of SVC, mean vascular density (VD) of the macular area and peripapillary was 47.698 ± 2.636% and 48.176 ± 2.916%, respectively. At the level of DCP, mean VD was 34.14 ± 3.54% in the macular area. At the level of DCP, the mean area, circularity, aspect ratio, roundness, and solidity of the foveal avascular zone (FAZ) were 14474.3±3811.67 μm2, 0.67±0.1, 1.16±0.1, 0.868±0.08, 0.895±0.038, respectively.
Conclusions :
OCTA enables non-invasive visualization of retinal and choroidal microvasculature in NHP with high resolution, providing quantifiable in vivo measurements for longitudinal analysis, suggesting that OCTA is useful for investigating novel therapies in animal models of NHP in preclinical ocular research.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.