Abstract
From a basic point of view, the crystalline lens of the eye (the "lens") can be described as a biconvex lens that provides approximately one-third (20D) of the total dioptric power of the eye. In reality, the lens is a much more complex optical system:The lens is aspheric and inhomogeneous, with a refractive index gradient (the "lens gradient") that plays a key role in determining its optical properties.
The lens is a dynamic optical element that changes shape during accommodation. Changes in lens shape allow the eye to change focus.
The lens continuously grows throughout life. Lens growth produces age-dependent changes in lens shape and refractive index gradient that affect the optical properties.
The lens transmission progressively decreases with age. Increased scattering within the lens produces a loss of transparency that eventually leads to age-related cataract.