Spontaneous ocular lesions in rhesus macaques with eye poking behavior

Abstract

Purpose : Non-human primates (NHPs) have similar postnatal visual development and ocular anatomy, particularly of the retina, to that of humans. Thus, identifying spontaneous ocular disease models in NHPs would be of great value to facilitate the development and testing of novel treatments. The purpose of this study was to describe the ocular examination and diagnostic findings in a NHP population at the California National Primate Research Center (CNRPC) with eye poking behavior.

Methods : Rhesus macaques identified by the CNPRC Behavior Service to exhibit eye manipulatory behavior (eye covering or poking on or below the globe) received a comprehensive ophthalmic examination including slit lamp biomicroscopy, indirect ophthalmoscopy, electroretinography, Fourier-domain optical coherence tomography (FD-OCT), rebound tonometry, streak retinoscopy and A-scan ultrasound biometry. Data are presented as mean ± SD.

Results : Of 102 NHPs with eye poking behavior, 69 (50 females and 19 males) were examined with a mean age of 12.2 ± 5.9 years. Fifty NHPs (72%) had an ophthalmic lesion in at least one eye localized to the fundus (n = 47) or lens (n = 16). The most common retinal lesions observed were fine, punctate flecks (n = 32), cuticular drusen (n = 7), foveal pigment (n = 4), intraretinal hemorrhages (n = 3), medium soft drusen (n = 1), and/or yellow subretinal peripheral lesions (n = 1); no retinal abnormalities were found in 22 NHPs. Achromatopsia was diagnosed in 4 NHPs by electroretinography and FD-OCT with an absent photopic ERG and foveal thinning, respectively. Mean IOP and refractive value were 16 ± 4 mm Hg and +1.5 ± 1.6 D, respectively. Moderate (+2.25-5 D) and severe (>+5 D) hyperopia was diagnosed in 4 and 2 NHPs, respectively. For individuals with no or low refractive error, vitreous and axial globe (AGL) lengths were 11.8 ± 0.87 and 19.7 ± 0.78 mm, respectively. By contrast, moderate to severe hyperopes had shorter globes with vitreous and AGL lengths of 10.5 ± 1.11 and 18.5 ± 1.06 mm, respectively. Presumed vision impairment due to achromatopsia (n = 4) or hyperopia (n = 6) was identified in 14% of NHPs examined with eye poking behavior.

Conclusions : A high incidence of ophthalmic lesions exists in NHPs with eye manipulatory behavior with a proportion predictive of vision impairment. Surveys of individuals within NHP colonies with these types of behaviors are recommended to identify novel spontaneous ocular disease models.

This is a 2020 ARVO Annual Meeting abstract.