Multimodal imaging of the retina and choroid in healthy Macaca fascicularis at different ages

Abstract

The aim of this study was to identify the morphological features of the retina and choroid in Macaca fascicularis of different ages using multimodal imaging. Methods A total of 27 Macaca fascicularis with no ocular diseases were studied (mean age, 104.2 months; range, 1.2-223.6 months). Multimodal imaging was obtained from each subject. The morphological features were compared within four subgroups according to age. Results On spectrum-domain optical coherence tomography (SD-OCT), four hyper-reflective bands could be observed in the outer retina in non-infant macaques (21/21, 100%), while the interdigitation zone could not be observed in the six infant macaques. A narrow hypo-reflective band just posterior to the retinal pigment epithelium (RPE) was noted in most eyes (25/ 27, 92.6%). The choroidal-scleral junction (CSJ) was visible in 83.3% of infants but only in 12.5% of adults and 14.3% of the geriatric population, and it could not be seen in juveniles. There was a significant difference in CSJ visibility between the infant group and the other three groups (P < 0.001). Tessellated fundus, in which the choroidal vessels are visible through the retina, could be observed clearly with near-infrared reflectance imaging (NIR). Some granular spots were noted in juveniles, and they accumulated dramatically with age, but were absent in infants. Conclusion Notable morphological features can be observed in the Macaca fascicularis subjects using multimodal imaging, and these features vary distinctly according to their age. It is important to note that infant macaques had no interdigitation zone, while the other macaques had no visible CSJ but did have well-defined choroidal capillaries. Age and the features should be considered seriously in future animal studies.

Requirement of age-dependent normalization of spectral-domain optical coherent tomography parameters in non-human primates for translational studies

“…OCTA has already been used in macaques affected by an experimental glaucoma and allowed to discover that, around the ONH, the inner retinal capillary density gradually decreased with increasing IOP, reaching statistical significance when pressure exceeded 50 mmHg, but returned when IOP was reduced [7]. Complementary experiments using OCTA are required for refining the conclusions stated in the recent report discussed here [4].…”

“…SD-OCT images of the retina and choroid evolve in monkeys since birth to geriatric ages. A recent report of results of enhanced depth imaging (EDI) OCT showed the visualization in non-infant Macaca fascicularis four hyper-reflective microlayers in the outer retina: the external limiting membrane (ELM), the ellipsoid zone (EZ), the interdigitation zone (IZ), and the RPE; whereas the IZ could not be detected in infant Macaca fascicularis [4]. Furthermore, NIR and SD-OCT allowed to detect choroidal vessels in non-infant macaques with certainty, whereas they were not detected or much more difficult to detect in infant macaques.…”

“…The measurement of choroidal thickness is only reliable and repeatable when a clear CSJ is observed. Of utmost importance, this report emphasizes the fact that, to date, the measurement of choroidal thickness using EDI SD-OCT in non-infant macaques is still impractical and provides with a very high probability false data [4]. For the future studies of inherited choroido-retinal dystrophies occurring at early stages in the novel NHP models, this observation should be taken into account seriously.…”

Comparison of vascular parameters between normal cynomolgus macaques and healthy humans by optical coherence tomography angiography

“…The FFA and OCT-A vascular parameters for normal humans have been previously reported. [1, 14, 15] Researchers have reported flow perfusion parameters for normal rhesus monkeys [16] and chorioretinal structure and stratification of cynomolgus macaques and rhesus monkeys by SD-OCT. [17, 18] However, very little literature is available on the vascular density parameters for the macular and optic disc of ocularly normal adult cynomolgus macaques, researchers have not clearly determined how OCT-A may be used for disease management, particularly in animal models, and the comparison of VD between healthy humans and cynomolgus macaques using OCT-A has not been conducted. Our study aimed to evaluate macular vascular circulation parameters in normal adult cynomolgus macaques using OCT-A.…”

Extensive Sub-RPE Complement Deposition in a Nonhuman Primate Model of Early-Stage Diabetic Retinopathy

“…[3][4][5][6] In addition, NHP is considered to be a powerful model of ocular diseases owing to its high structural resemblance to human. 7,8 With this appropriate model, we have observed some of the vascular complications that occur in DR patients. [9][10][11] Recognition of early-stage DR characteristics and understanding of the mechanism underlying the initiation of DR are essential for the prevention and control of this disease.…”