Prevalence and Characteristics of Myopia in Adult Non-Human Primates in Southwest China.

PURPOSE: To investigate the prevalence of myopia in a large cohort of adult cynomolgus monkeys (Macaca fascicularis) at Yunnan Province in southwest China and describe the characteristics of myopic rhesus macaque eyes.

METHODS

A total of 219 cynomolgus monkeys 14.07 ± 2.72 years old (range, 8-21) were randomly recruited for this study. We performed fundus photography and measurements of cycloplegic refractive error (RE) and axial length (AL) on macaques.

RESULTS

A total of 429 eyes of 219 macaques were examined. The median RE was -1.25 diopters (D), and the median AL was 18.69 mm. The prevalence of myopia was 62.47%, and one-third of the myopic eyes were highly myopic. The presence of fundus tessellations was higher in myopic eyes than non-myopic eyes (42.54% vs. 6.21%). The cutoff value for the presence of tessellations was -3.52 D for RE and 19.38 mm for AL. In myopic eyes, there were significant differences between grade 1 and grade 3 fundus tessellations on RE (-5.57 ± 2.97 D vs. -8.13 ± 3.51 D) and AL (19.66 ± 0.55 mm vs. 20.60 ± 1.06 mm). Beta-peripapillary atrophy (β-PPA) was found in 48.10% of myopic eyes and 6.83% of non-myopic eyes. The presence of β-PPA is associated with the presence of fundus tessellations, AL, and RE. The presence of β-PPA was higher in grade 3 than grade 1 fundus tessellations (94.4% vs. 76%).

CONCLUSIONS

More than half of adult cynomolgus monkeys in southwest China are myopic, and one-third of the myopic ones are highly myopic. Similar to humans, tessellated fundi and β-PPA are the characteristic signs of myopic cynomolgus monkeys. Adult cynomolgus monkeys are optimal animal models for research on the pathogenesis of myopia.

TRANSLATIONAL RELEVANCE: This study not only provides a reference for the refractive state and AL in myopic cynomolgus monkeys but also indicates that adult cynomolgus monkeys with spontaneous myopia are optimal animal models for research on the pathogenesis of myopia.