Panoramic view of retinal and choroidal circulation and structures in vivo based on ultra-widefield OCT/OCTA: from animal to human

This study aimed to compare retinal and choroidal circulation and structural parameters between humans and five commonly used experimental animals (rats, mice, guinea pigs, rabbits, and monkeys) using ultra-widefield swept-source optical coherence tomography (SS-OCT) and SS-OCT angiography (SS-OCTA). The study found that the six species exhibited unique patterns in retinal and choroidal vessel flow distribution. Rats and mice demonstrated significantly higher retinal and choroidal vessel flow density (VFD) compared to humans, while retinal vessels in rabbits are confined to a broad horizontal band, and in guinea pigs are restricted to the peripapillary area. Monkeys displayed retinal vessel flow patterns highly similar to humans, but with a higher vessel flow density in the deep capillary plexus (DCP) within the central region. Retinal and choroidal thicknesses were consistently thinner in rodents and rabbits than in humans, and monkeys displayed a thinner inner retinal layer (IRL) and choroid in the central region. Regarding optic nerve head parameters, both monkeys and rabbits showed smaller optic cup area and rim area compared to humans. However, no significant difference in the cup-to-disc ratio (CDR) was observed between humans and monkeys, whereas rabbits exhibited a significantly higher CDR. These results demonstrate significant interspecies variations in retinal and choroidal circulation, thickness, and optic nerve head structure. The findings provide a reference framework for the careful selection of animal models in ophthalmic research, facilitating a better understanding and application of these models to simulate human ocular diseases.