New approximation for the whole profile of the human crystalline lens.

This paper presents a new approximation for the whole profile of the human crystalline lens by the use of only one analytical function for both unaccommodated lens and the lens on accommodation. Approximation of the anterior and posterior lens profile is composed of hyperbolic cosine functions and is given in polar coordinates. Each of the hyperbolic cosines is modulated by the function of hyperbolic tangent type. The curvature of the hyperbolic cosine in polar coordinates is discussed and some results concerning the stability of its central radius of curvature are shown. Fitting of the hyperbolic cosine type curve to various results of the lens curvature measurements is presented. Examples of profiles of the lens under accommodation are given. It is shown that this approximation can be used for the description of iso-indical profiles inside the lens.