To examine parameters of the cornea, retina, intraocular pressure, and visual electrophysiology of three-year-old rhesus monkeys.

In this descriptive study, 8 three-year-old rhesus monkeys were selected for measurement of intraocular pressure (IOP), spherical equivalent (SE), anterior chamber depth (ACD), lens thickness (LT), vitreous chamber depth (VCD), axial length (AL), central corneal thickness (CCT), retinal thickness, choroidal thickness (under fovea and 500, 1 000, 1 500 μm nasal or temporal from fovea), and flash electroretinogram (f-ERG). The measurements were made by TonoVet tonometry, A-scan ultrasonography, optical coherence tomography (OCT), and visual electrophysiology. Paired t-tests were used to analyze differences between left and right eyes. Repeated ANOVA was used to analyze differences of choroidal thickness at different locations.

The IOP of three-year-old rhesus monkeys was 16.9±3.1 mmHg, the SE was +0.6±1.0 diopter(D), the ACD was 3.4±0.4 mm, the LT was 3.8±0.2 mm, the VCD was 12.3±0.5 mm, the AL was 19.5±0.6 mm, the CCT was 537.6±50.8 μm, the foveal retinal layer thickness was 206.8±16.0 μm, and the foveal choroidal thickness was 186.6±17.2 μm. There were significant differences of choroidal thickness among all locations (F=10.966, P<0.001). There was a significant difference between foveal choroidal thickness and choroidal thickness at all extrafoveal locations (P<0.05).The amplitude of the dark-adapted rod-response b-wave was 170.3±41.7 μV. The amplitude of standard combined ERG a-wave was 195.4±37.4 μV, and the b-wave was 373.0±70.1 μV. The amplitude of cone-response a-wave was 26.1±6.6 μV and the b-wave was 105.4±35.7 μV. There were no statistically significant differences in any of the measured ocular biometry values between left and right eyes.

The reliable and complete ocular parameters of three-year-old rhesus monkeys will lay the foundation for future ocular research.

Macaca mulatta; Intraocular pressure; Retina; Choroid; Visual electrophysiology