Ocular measurements throughout the adult life span of rhesus monkeys.
OBJECTIVE
To examine the relationship of ocular components to refraction throughout the adult life span of the rhesus monkey (Macaca mulatta).


METHODS
Cycloplegic retinoscopy, A-scan ultrasonography, slit lamp examination, indirect ophthalmoscopy, and keratometry were performed in a cross-sectional study of 111 monkeys, aged 5 to 31 years. Lens thickness and anterior and vitreous chamber depths were measured from the echograms. The intercorrelations of these variables were analyzed, as well as their association with age and sex.


RESULTS
In monkeys aged 5 to 15 years, the mean refractive value of +1.5 D with an SD of 1.7 D was maintained near the previously established developmental asymptote of +2 D. In monkeys older than 15 years, there was greater interindividual variation (SD = 4.5 D), including extreme myopia and hyperopia. The cornea became steeper with age. The axial length of the eyes increased up to 12 years of age and began to shorten after 20 years. Changes also occurred in the other individual components that constitute eye length. These age-related changes were decreased vitreous chamber depth, decreased anterior chamber depth, and increased lens thickness. In general, males had longer eyes than females. The eyes of old monkeys were more likely to exhibit cataract and drusen, but age-related changes in focal atrophy of the retinal pigment epithelium did not achieve statistical significance.


CONCLUSIONS
The components of the monkey eye change with age in a pattern similar to that reported in humans. Age-related changes in individual ocular components that could be detrimental to refraction appear to be compensated for by changes in other components.
Fernandes
Alcides
A
Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30322, USA. alcides@rmy.emory.edu
Bradley
Dolores V
DV
Tigges
Margarete
M
Tigges
Johannes
J
Herndon
James G
JG
D000375:Aging / Q000502:physiology*; D000818:Animals; D000867:Anterior Chamber / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D003315:Cornea / Q000502:physiology; D003430:Cross-Sectional Studies; D005123:Eye / Q000033:anatomy & histology*; D005260:Female; D007908:Lens, Crystalline / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D008253:Macaca mulatta / Q000033:anatomy & histology*; D008297:Male; D009887:Ophthalmoscopy; D012029:Refraction, Ocular / Q000502:physiology*; D014463:Ultrasonography; D014822:Vitreous Body / Q000033:anatomy & histology / Q000000981:diagnostic imaging