Purchase this article with an account.
Mary Ann A. Croft, Jared P. McDonald, Alexander W. Katz, Paul L. Kaufman; Extralenticular And Lenticular Factors In Accommodation And Presbyopia: Human & Monkey. Invest. Ophthalmol. Vis. Sci. 2011;52(14):3408.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To compare the human eye to the monkey eye with respect to the ciliary body, lens and zonular attachments at rest and during accommodation in subjects and monkeys of various ages.
The eyes of 24 rhesus monkeys (aged 4-28 yrs) and 12 human subjects (aged 19-65 yrs) were studied. Central electrical stimulation of the Edinger-Westphal (E-W) nucleus was used to induce maximum accommodative responses in the monkey and pharmacological stimulation (2 drops 4% pilocarpine) was used to induce accommodation in the human eye. Analogous ultrasound biomicroscopy (UBM; 50 MHz, 35 MHz) images were collected in both species to compare ciliary body configuration, lens and zonular attachments. The entire extent of the ciliary body, zonula, and the anterior and posterior surfaces of the lens were imaged before and during accommodation.
The thickening of the human ciliary muscle apex during accommodation was significantly related to accommodative amplitude (slope = 28.0 ± 9.53 diopters/mm; p=0.015; r=0.68), and the apex thickening declined significantly with age and in parallel with the age-related loss in accommodative amplitude. Accommodative lens thickening declined with age in both species. The results were similar in the monkey eye, but age-related loss of muscle movement was less pronounced. The accommodative forward movement of the vitreous zonule insertion zone declined with age in both the human (by 85%; n=5; p=0.01) and the monkey (by 60%; n=4; p=0.028). There are age-related changes in the geometry of the various accommodative structures, which likely impact functional relationships in both species. Orientation/geometry of the ciliary body, lens and zonula in the young and old human vs. the monkey will be discussed.
The more pronounced loss in ciliary body movement in the human eye vs. the monkey eye could be due to the fact that the insertion zone of the vitreous zonule is far thicker in the human and could restrict muscle movement with age. There was a pronounced age-related loss in forward and centripetal ciliary body movement in the human eye, which may impact accommodating IOL function. The monkey remains the best model for human accommodation and presbyopia.
This PDF is available to Subscribers Only