Finite Element Method-Simulation of the Human Lens during Accommodation

摘要

A finite-element-method model with ANSYS 8.0 of a 29 year old human lens during accommodation will be presented. The required data, to draw and calculate a two dimensional, axis-symmetric model of the human lens is inherited from various sources. Furthermore the analysis premises all lens materials to be linear elastic and allows large displacements. A first analysis of a possible method for the treatment of presbyopia by fs-laser induced microcuts is accomplished. Therefore a mechanical analysis of an untreated and a treated lens are compared. As a result an improvement of the flexibility of the lens tissue is found and as its consequence a change of the lens' radii of curvature is established. After a suitable processing of the output data a linear Gaussian ray trace is performed and a minor change in the optical power between the untreated and treaded human lens is perceived. By calculation of the discrete optical power of the anterior and posterior surface on the one hand and the overall optical power on the other hand an interpretation of the effectiveness resulting from the treatment is offered. It is ascertained that the change in optical power of the anterior lens surface is increased while the optical power of the posterior lens surface is decreased, almost compensating each other. A possible explanation for this phenomenon is given and a suggestion of how to increase the effectiveness of the treatment is discussed.