Pierscionek B K, Weale R A
Department of Electronic Engineering, Latrobe University Bundoora Victoria, Australia.
Doc Ophthalmol. 1995;89(4):321-35. doi: 10.1007/BF01203708.
Although the lens of the eye is structurally a biological tissue, it functions as an optical element providing one third of the refracting power of the human eye, and a variable focus in younger years. Throughout a life-time the optical properties of the eye-lens alter, resulting in changes in function: there is a gradual depletion of the focussing amplitude from infancy to middle age, and a loss of transmittance in the later decades of life. The optical properties of the lens depend on its power, which in turn is determined by its physical dimensions (curvatures and thickness) and its refractive index as well as transmissivity and the organization of its internal components. The power of the functional lens is, however, modifiable by virtue of the lens being attached via the zonule to the ciliary muscle. The contraction and relaxation of the latter respectively increases and decreases lens power in accordance with innervations determined by the physical distance of external objects to be imaged on the retina. This review will consider many of these features and how alterations in any of them may lead to changes in lenticular function. However, as we have recently devoted a detailed study to presbyopia [1] its mechanism will not be considered here.
尽管眼睛的晶状体在结构上是一种生物组织，但它作为一个光学元件发挥作用，提供人眼三分之一的屈光力，并在年轻时具有可变焦距。在整个生命周期中，晶状体的光学特性会发生改变，从而导致功能变化：从婴儿期到中年，聚焦幅度逐渐减小，而在生命的后几十年，透光率会下降。晶状体的光学特性取决于其屈光力，而屈光力又由其物理尺寸（曲率和厚度）、折射率、透光率以及内部成分的组织结构决定。然而，功能性晶状体的屈光力是可调节的，因为晶状体通过小带附着于睫状肌。睫状肌的收缩和舒张分别根据外部物体在视网膜上成像的物理距离所决定的神经支配，增加和降低晶状体的屈光力。本综述将探讨其中的许多特征，以及其中任何一个特征的改变如何可能导致晶状体功能的变化。然而，由于我们最近对老花眼进行了详细研究[1]，这里将不再考虑其机制。
