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N. M. Ziebarth, D. Borja, F. Manns, V. T. Moy, J.-M. Parel; Relationship Between Elasticity and Dioptric Power of Whole Cadaver Primate Crystalline Lenses. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3793. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the relationship between primate whole lens elasticity measured by atomic force microscopy (AFM) and dioptric power.
Measurements were performed on intact lenses of 23 non-fixed cynomolgus eyes (4-10 years, <1 day postmortem) and 4 human eyes (26-82 years, <3 days postmortem) that were left attached to the zonule-ciliary body-sclera framework. The eyes were prepared by bonding a plastic ring on the sclera after removal of conjunctiva, adipose, and muscle tissues. The posterior pole was sectioned and excess vitreous was removed. The anterior vitreous and hyaloid membrane were left intact. The eye’s anterior section was placed on a Teflon slide and the cornea and iris were removed. The lens-zonule-ciliary body-sclera section was then placed in a Petri dish filled with DMEM in a laboratory-built AFM system designed for force measurements (Ziebarth et al, Mol Vis, 2007). The central pole of the anterior lens surface was probed with the AFM. The recorded deflection-indentation curves were used to derive force-indentation curves. Young’s modulus was calculated from the force-indentation relation using the model of Hertz (Timoshenko, Theory of Elasticity 1934). After elasticity measurements, the dioptric power of the lens was measured using a modified commercial lensmeter.
Young’s modulus ranged from 0.4kPa-2.9kPa for monkey eyes and 0.8kPa-29.4MPa for human eyes. Young’s modulus was not dependent on age in monkey eyes (p=0.26), although this relationship was significant in human eyes (p=0.06). Dioptric lens power ranged from 39.8-52.1D for monkey and 16.8-26.8D for human. Power decreased significantly in both monkey and human lenses as age (p=0.023 and p=0.057, respectively), and Young’s modulus increased (p=0.09 and 0.23, respectively).
There a direct relation between the lens power in its maximally accommodated state (isolated lens) and lens elasticity. As Young’s modulus of the lens increases, its maximally accommodated power decreases.Support: NIH 2R01EY14225; NSF Graduate Student Fellowship; NIH 5F31EY15395; Florida Lions Eye Bank; the Australian Federal Government CRC Scheme through the Vision Cooperative Research Centre; AMO Inc, Santa Ana, CA; NIH center grant P30-EY014801; Research to Prevent Blindness; Henri and Flore Lesieur Foundation; NSF-BITC; NIH GM55611; Scientific Advisory Committee, University of Miami.
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