AGING OF HUMAN CRYSTALLINE LENS DYNAMICS

本研究的主要目标是定量表征 人类调节机制与年龄依赖性调节损失 （老花眼）在成人正视。 住宿，这一过程， 人眼聚焦于附近的物体，通过控制变化发生， 晶体透镜的形状。 人们普遍认为，作为纤毛 当肌肉收缩时，透镜通过弹性或粘弹性的 导致沿极轴沿着厚度增加的弛豫， 前房变浅，沿前房厚度沿着增加 前、后透镜表面的曲率;后两者 事件的作用是增加地球仪的总折射能力。 与 随着年龄的增长，振幅减小， 逐渐消退，一般导致50岁的需要， 光学假体 这种年龄依赖性退化的原因是 退化的范围已被各种归因于退化的 睫状肌，晶状体透镜的生长和/或硬化， 玻璃体的膨胀和几何关系的变化 穿过小带在透镜和睫状肌之间。 我们计划使用 我们收集了149名成人正视眼受试者的数据， 年龄为18岁和70岁，包括厚度测量结果， 角膜曲率测量、超声检查和Scheimpflug裂隙灯摄影， 表征人眼的老化，尤其是透镜，以及 调节过程和老花眼的发展。 统计 这些数据的分析将允许识别和表征 年龄依赖性和非年龄依赖性参数的相互作用 住宿. 透镜弹性特性的并行表征 使用新鲜的死后人类晶状体将直接测试假设， 透镜随年龄增长而变硬。 这些数据将用于应用 两个新的计算机为基础的住宿模式，以研究老龄化的 调节过程和晶状体相关结构的作用 这个过程 这些数据也可以用来研究--最终 解决“透镜悖论”。

The primary goal of this research is to characterize quantitatively the mechanism of human accommodation and age-dependent accommodative loss (presbyopia) in adult emmetropes. Accommodation, the process by which the human eye focuses on near objects, occurs through controlled changes in the shape of the crystalline lens. It is generally held that, as the ciliary muscle contracts, the lens goes through an elastic or visoelastic relaxation that results in an increased thickness along the polar axis, a shallowing of the anterior chamber, and increased thickness along the curvature on the anterior and posterior lens surfaces; the latter two events act to increase the overall refractive power of the globe. With increasing age, accommodative amplitude decreases such that the near point gradually recedes, leading generally by the age of 50 yr to the need for optical prostheses. The causes of this age-dependent degradation of accommodative range have been attributed variously to degeneration of the ciliary muscle, growth and/or hardening of the crystalline lens, liquefication of the vitreous, and changes in the geometric relationship between the lens and ciliary muscles through the zonules. We plan to use the data we have collected on 149 adult emmetropic human subjects between the ages of 18 and 70 yr, which includes results from pachymetry, keratometry, ultrasonography, and Scheimpflug slit-lamp photography, to characterize the aging of the human eye, especially the lens, and both the process of accommodation and the development of presbyopia. Statistical analysis of these data will allow identification and characterization of the interaction of age-dependent and -independent parameters in accommodation. Concurrent characterization of lens elastic properties using fresh post-mortem human lenses will directly test the hypothesis of lens stiffening with age. These data will be used in the application of two new computer-based accommodation models to the study of the aging of the accommodation process and the roles of lens-associated structures in this process. These data can also be used to study - and eventually resolve - the "lens paradox".