Correlation between spherical equivalent and biometry parameters in adult Cynomolgus macaque

Area of Science:

• Ophthalmology
• Primate Research
• Comparative Biology

Background:

• Understanding refractive error distribution and influencing factors is crucial for developing effective interventions.
• Cynomolgus monkeys are increasingly used as models in biomedical research, necessitating characterization of their ocular parameters.

Purpose of the Study:

• To characterize the distribution of refractive and ocular biometry parameters in cynomolgus monkey colonies.
• To analyze the factors influencing refractive status in these non-human primates.

Main Methods:

• A population-based, cross-sectional study involving 263 adult cynomolgus monkeys (520 eyes).
• Measurements included intraocular pressure, cycloplegic refraction (spherical equivalent - SE), corneal radius of curvature (CRC), anterior chamber depth (ACD), lens thickness (LT), axial length (AL), central corneal thickness (CCT), and choroidal thickness (ChT).
• Multiple regression analysis was used to identify associations between refraction and ocular biometry.

Main Results:

• Prevalence of refractive errors: 29.42% hyperopia, 27.12% emmetropia, 33.27% mild-to-moderate myopia, 10.19% high myopia. Mean SE was -1.27 ± 3.44 D.
• Key biometric findings: Mean AL was 18.76 ± 0.89 mm, mean CRC was 5.70 ± 0.22 mm, mean CCT was 454.30 ± 32.40 μm, mean ChT was 188.96 ± 38.19 μm.
• Axial length (AL) alone explained 40.5% of SE variance; age, AL, and CRC together explained 57.5%.

Conclusions:

• Refractive characteristics and ocular biometry in cynomolgus monkeys closely resemble those in humans.
• Axial length, corneal radius of curvature, and choroidal thickness exhibit similar variation patterns to humans.
• Cynomolgus monkeys with naturally occurring refractive errors represent a valuable animal model for studying refractive development and interventions.