ABSTRACT
The ocular lens is an isolated epithelial tissue encased by a thick capsule and supported by zonular suspensory ligaments. The primary function of the lens is to aid in the focusing of light onto the retina and, during accommodation with a young deformable lens, to dynamically adjust the focus from distant to near objects. Refraction of the lens is enhanced by its biconvex-oblate-spheroidal shape, transparency, high internal refractive index, and radial gradient of refractive index that reduces spherical aberration (61,104,118). The cortical outer layer, about 1mm thick in adult human lenses, contains compact highly organized cells and has a refractive index that gradually increases toward the interior. The inner nuclear mass has densely packed cells with high protein concentration and high constant refractive index (118). The lens shape, optical properties, and internal organization are the result of a unique pattern of development and differentiation (95).
