Schachar R A, Abolmaali A, Le T
Department of Physics, University of Texas at Arlington, Arlington, TX, USA.
Br J Ophthalmol. 2006 Oct;90(10):1304-9. doi: 10.1136/bjo.2006.100347. Epub 2006 Jul 19.
To understand the effect of the geometric and material properties of the lens on the age-related decline in accommodative amplitude.
Using a non-linear finite-element model, a parametric assessment was carried out to determine the effect of stiffness of the cortex, nucleus, capsule and zonules, and that of thickness of the capsule and lens, on the change in central optical power (COP) associated with zonular traction. Convergence was required for all solutions.
Increasing either capsular stiffness or capsular thickness was associated with an increase in the change in COP for any specific amount of zonular traction. Weakening the attachment between the capsule and its underlying cortex increased the magnitude of the change in COP. When the hardness of the total lens stroma, cortex or nucleus was increased, there was a reduction in the amount of change in COP associated with a fixed amount of zonular traction.
Increasing lens hardness reduces accommodative amplitude; however, as hardness of the lens does not occur until after the fourth decade of life, the age-related decline in accommodative amplitude must be due to another mechanism. One explanation is a progressive decline in the magnitude of the maximum force exerted by the zonules with ageing.
了解晶状体的几何和材料特性对与年龄相关的调节幅度下降的影响。
使用非线性有限元模型进行参数评估，以确定皮质、核、囊膜和悬韧带的硬度以及囊膜和晶状体厚度对与悬韧带牵引相关的中央屈光力（COP）变化的影响。所有解都需要收敛。
对于任何特定量的悬韧带牵引，增加囊膜硬度或囊膜厚度都与COP变化增加相关。削弱囊膜与其下方皮质之间的附着会增加COP变化的幅度。当整个晶状体基质、皮质或核的硬度增加时，与固定量的悬韧带牵引相关的COP变化量会减少。
增加晶状体硬度会降低调节幅度；然而，由于晶状体硬度直到生命的第四个十年之后才会出现，与年龄相关的调节幅度下降必定是由于另一种机制。一种解释是随着年龄增长悬韧带施加的最大力的大小逐渐下降。
