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J.-M. A. Parel, F. Manns, E. Arrieta-Quintero, M. Taneja, P. Vaddavalli, D. Nankivil, N. Ziebarth, P. Veerendranath, A. Mohamed, V. Sangwan; Age-related Changes in the Mechanical Properties of the Human Ciliary Body. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4290.
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© ARVO (1962-2015); The Authors (2016-present)
To quantify the changes in elastic properties of the ciliary body with age and the potential implications for presbyopia.
The mechanical response of the ciliary body was evaluated in a lens stretcher (EVAS I, Parel et al, ARVO 2002). The EVAS I system radially stretches the outer sclera of tissue preparations containing the intact lens, lens capsule, zonules, ciliary body and surrounding sclera. The outer sclera diameter is increased by 4 mm in diameter in 0.5mm steps. The ciliary ring diameter and load are measured at each step. Stretching produces a radial extension of the ciliary ring equal to the total outer scleral displacement (4 mm) minus the increase in ciliary ring diameter. The elasticity (in mm/g) of the ciliary ring is estimated by dividing the radial extension of the ciliary ring (in mm) by the load at maximum stretch (g). The ciliary ring elasticity was calculated for a total of 84 human lenses (age =1 day to 85 years, postmortem time = 24 to 120 hours) obtained from the LV Prasad Eye-Bank in India and several American Eye-Banks. The age-dependence of the ciliary ring elasticity (mm/g) and of the unstretched (no tension applied) ciliary ring diameter (mm) were quantified.
The elasticity of the ciliary body is independent of age, with an average value (+/- SD) of 0.36+/-0.13 mm/g. Overall, the unstretched ciliary ring diameter decreases with age (p=0.006). The trend was non-linear with most of the decrease occurring after the age of 30 years.
The ciliary body retains its elastic properties throughout life. The decrease in the ciliary ring diameter with age is consistent with published in vivo data but the in vitro results suggest that the effect occurs after most of the accommodation amplitude is lost. Together these findings suggest that the ciliary body does not contribute significantly to the loss of accommodation with age leading to presbyopia.Support: NIH EY14225; Australian Federal Government CRC Scheme through the Vision Cooperative Research Centre; Florida Lions Eye Bank; Dr Rakhi Jain , AMO Inc, Santa Ana, CA; NIH center grant P30-EY014801; Research to Prevent Blindness. Henri and Flore Lesieur Foundation (JMP).
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