PubMed ID: 42444145
Author(s): Nork TM, Sonnentag PJ, Miller PE, Wabers HD, Rasmussen CA, Katz AW, Kim CBY, Ver Hoeve JN, Eaton JS, Bentley E, Christian BJ, O’Neill CA, Crosson CE, Murphy CJ. Preexisting Fundus Findings in a Large Cohort of Young Cynomolgus Macaques (Macaca fascicularis) Bred for Ocular Research: Comparison to Humans. J Ocul Pharmacol Ther. 2026 Jul 13:10807683261466791. doi: 10.1177/10807683261466791. Online ahead of print. PMID 42444145
Journal: Journal Of Ocular Pharmacology And Therapeutics : The Official Journal Of The Association For Ocular Pharmacology And Therapeutics, Jul 2026
PURPOSE To categorize preexisting fundus findings in a large group of healthy young adult cynomolgus macaques [nonhuman primates (NHPs)] and to compare them to similar conditions in young human retinas.
METHODS During the past 30 years, more than 20,000 young purpose-bred cynomolgus macaques were screened prior to enrollment in nonclinical pharmaceutical development studies at a single contract research organization. The fundus findings were documented by clinical examinations, various retinal imaging modalities, and/or visual electrophysiological testing.
RESULTS Sheen from the internal limiting membrane (ILM) was common in these young adult NHPs as it is in young humans. Infrequent in both NHPs and humans were cilioretinal arteries. Small patches of retinal pigment epithelial (RPE) depigmentation were common, for which there is no human correlate. Likewise, there is no exact human correlate for foveal drusen-like spots in the young NHPs. Also common in NHPs but uncommon in humans were remnants of the fetal vasculature. Conditions rare in both NHPs and humans included myelinated nerve fiber layer, astrocytic hamartoma, coloboma, and congenital hypertrophy of the RPE. Notable rare abnormal findings included a white dot condition, a large macular tumor, and idiopathic optic atrophy, all of which were of unknown etiology.
DISCUSSION Preexisting abnormalities, when taken together, are common in NHPs and can occasionally complicate the assessment of toxicity from test articles subsequently administered, impacting the clinical development of test articles. As such, it is critical that NHPs be prescreened and, ideally, the fundus appearance be documented with fundus imaging when enrolled in preclinical studies.