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Mary Ann Croft, Gregg Heatley, T Michael Nork, Jared McDonald, Alex Katz, Julie Kiland, Paul Kaufman; Accommodative Movements of the Lens/Capsule in Relation to the Vitreous Face and Aging. Invest. Ophthalmol. Vis. Sci. 2013;54(15):386.
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© ARVO (1962-2015); The Authors (2016-present)
To elucidate the accommodative movements of the posterior lens/capsule in the human eye at various ages in comparison to the monkey eye before and after extracapsular lens extraction (ECLE).
The eyes of 6 rhesus monkeys (aged 8-22 yrs) and 12 human subjects (aged 19-65 yrs) were studied. Maximum accommodative responses were induced in the human eyes by pharmacological stimulation (2 drops 4% pilocarpine) and in the monkey eyes by central electrical stimulation of the Edinger-Westphal (E-W) nucleus. Ultrasound biomicroscopy (UBM; 50 MHz, 35 MHz) images were collected in the region of the lens/capsule, ciliary body, and zonular attachments in both species.
During accommodation in the human eyes, the posterior pole of the lens moved posteriorly by 0.08 ± 0.01 [mean ± s.e.m.] mm (n=4) and 0.01 ± 0.03 mm (n=4) in the young and middle-aged eyes, respectively, and in the older eyes the posterior pole of the lens moved forward during accommodation by -0.08 ± 0.04 mm (n=4). Over the entire age range for the human subjects, the posterior lens movement declined by 0.0049 ± 0.0008 mm/year (p=0.001, r=0.86). Similar results were seen in the phakic monkey eyes. Following ECLE the capsule bowed backward in all 6 monkeys during accommodation. In the three monkey eyes in which measurements were taken, the posterior capsule bowed backward during accommodation by 0.70 ± 0.03 mm, 0.45 ± 0.02 mm, and 0.26 ± 0.03 mm in the 8-, 17-, and 22-year-old monkeys, respectively.
During accommodation, the vitreous allows a small amount of posterior movement of the posterior pole of the lens and allows pronounced backward movement of the capsule following ECLE, but this posterior accommodative movement declines with age. These findings may have implications for the mechanism of accommodation and presbyopia and the function of accommodating IOLs.
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