Comparison of retinal parameters between rhesus and cynomolgus macaques

Abstract

Non-human primates are important research models for basic vision research, preclinical pathogenesis and treatment studies due to strong similarities in retinal structure and function with humans. We compared retinal parameters between healthy normal rhesus macaques (Macaca mulatta) and cynomolgus macaques (Macaca fascicularis) by optical coherence tomography and electroretinography. The retinal parameters of 10 male rhesus macaques and 10 male cynomolgus macaques were compared. The Heldelberg Spectralis^® HRA+OCT and Roland multifocal electrophysiometer were used to analyze retinal morphology, multifocal electroretinogram (mfERG), and full-filed electroretinogram (ff-ERG). Mean retinal thickness was lowest in the central fovea of macaques and did not differ significantly between species, but the retinal thickness of the nerve fiber ganglion cell layer and the inner plexiform layer were significantly different. The amplitude density of the N1 wave is lower in rhesus macaques than in cynomolgus macaques in ring and quadrant areas between species. Dark-adapted 3.0 oscillatory potentials (reflection of amacrine cells’ activity) and light-adapted 30hz flicker ERG (a sensitive cone-pathway-driven response) waveforms of the ff-ERG were similar in both species while the time reached peaks in dark-adapted 0.01 ERG (the rod-driven response of bipolar cells) and dark-adapted 3.0 ERG (combined rod and cone system responses) as well as the implicit time of a-wave and b-wave in light-adapted 3.0 ERG (the single-flash cone response) really differed. This study provides normative retinal parameters for nonhuman primate research on basic and clinical ophthalmology, as well as a reference for researchers in the appropriate selection of rhesus or cynomolgus macaques as models for ophthalmology studies.