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D. Nankivil, B. Maceo, J. Dias, D. Borja, E. Arrieta-Quintero, F. Manns, J.-M. Parel; Estimation of Zonular Tension in Cynomolgus Monkeys during Lens Stretching by Transecting Anterior or Posterior Zonules: A Pilot Study. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2798.
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To estimate the change in tension of the zonular fibers inserting in the anterior and posterior lens during simulation of accommodation in a lens stretcher.
Eight post-mortem (11±11 hours) Cynomolgus monkey (Macaca fascicularis) eyes from seven monkeys (6.1±1.0 years old) were dissected leaving intact the lens, zonules, ciliary body, hyaloid membrane, most anterior vitreous and a segmented scleral rim. The lens preparation was mounted in an optomechanical lens stretching system (Ehrmann et al, Clin Exp Optom 2008;91:3:302-312) and the sclera was stretched 2mm radially in a step-wise fashion (0.25mm/step). The load and ciliary body diameter were measured at each step. The zonular fibers connecting to the anterior (n = 6) or posterior (n = 2) lens were then carefully transected using a diamond blade and the experiment was repeated. The diameter of the ciliary body processes was recorded. The tension on the anterior or posterior zonules was estimated by comparing the change in the ciliary body-load relationship before and after zonular transection.
During stretching, the ciliary body diameter increased linearly as a function of load. The amount of load required for a one millimeter increase in ciliary body diameter was reduced in all 8 eyes after transection of the anterior (p = 0.032) or posterior (p = 0.264) zonules. The ciliary body required 2.39±0.53g per millimeter of increase in diameter before, and 1.41±0.19g after anterior zonular transection, and 3.63±0.07g before and 2.59±0.66g after posterior zonular transection.
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