Aging of Nonhuman Primate Eyes Is Sexually Dimorphic

To characterize sex-specific and offspring number-associated patterns of ocular aging in Macaca fascicularis.

Comprehensive ophthalmic examinations were performed on 94 adult macaques (47 males, 47 females). Ocular biometry (lens thickness [LT], anterior chamber depth [ACD], axial length), nuclear lens density (NLD), macula retinal thickness, and retinal nerve fiber layer thickness (RNFLT) were assessed using IOLMaster and swept-source optical coherence tomography. Cataract and drusen were diagnosed using clinical imaging criteria. Sex-specific age associations were examined using correlation. Offspring number analyses included 16 females and 24 males with confirmed reproductive records.

Females and males differed significantly in ocular dimensions, with females showing smaller eyes and thinner retinas. Cataract prevalence was significantly higher in females compared to males (19.2% vs. 4.3%, P = 0.0286), whereas drusen prevalence was similar between sexes (17.0% in females vs. 14.9% in males). Although NLD and LT increased and ACD decreased with age in both sexes, aging slopes were consistently steeper in females. Increasing offspring number was associated with significant reductions in RNFLT in females, independent of age, while lens-related parameters showed no significant association with offspring number in either sex.

Female macaques exhibit accelerated lens aging and increased cataract susceptibility, mirroring patterns observed in human populations. Offspring number selectively contributes to neuroretinal thinning, suggesting a reproductive influence on retinal decline that is distinct from lens aging. These findings highlight the importance of considering sex and reproductive history in NHP-based ocular aging studies and provide biological insights relevant to human age-related eye disease.