Graduate Studies


First Advisor

Ryan M. Pedrigi

Date of this Version



Berggren, C.C., 2019. Finite Element Analysis of Altered Lens Capsule Mechanics After Cataract Surgery. M.S. thesis, University of Nebraska-Lincoln, Lincoln, NE.


A THESIS Presented to the Faculty of the Graduate College at the University of Nebraska in Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Mechanical Engineering and Applied Mechanics, Under the Supervision of Professor Ryan M. Pedrigi. Lincoln, Nebraska: November, 2019.

Copyright 2019 Caleb C. Berggren


Cataract surgery is the most common surgical procedure in the United States and is currently the only treatment for correcting the blurred vision that results from cataracts. This procedure requires cutting a permanent hole in the lens capsule and completely removing the underlying clouded lens fibers, which are exchanged for an intraocular lens (IOL) that is held in place by the remaining capsular bag. Current issues after surgery include the inability of IOLs to fully recover youthful accommodation, posterior capsule opacification (PCO) and capsule contraction. The latter two are thought to be a dysfunctional fibrotic response of the remnant lens epithelial cells (LECs) to the significant mechanical perturbation that occurs during cataract surgery. Although previous investigators have developed mechanical models of the lens fibers and surrounding lens capsule to study accommodation and the development of presbyopia, little work has been done to model the post-surgical lens capsule. Furthermore, most models have used homogeneous, linear, and isotropic material properties despite the capsule displaying heterogeneous, nonlinear, and anisotropic behavior. Herein, we have developed the first model of a post-surgical lens capsule with an implanted IOL. This is also the first fully 3-D model of the whole lens capsule with regionally-varying, nonlinear, and anisotropic material properties. We report significant changes from normalcy in the post-surgical lens capsule mechanical environment as a result of IOL implantation, supporting the hypothesis that altered lens capsule mechanics drives the long-term fibrotic LEC response after surgery. This model may also assist in the development of improved IOL designs that minimize PCO and capsule contraction and fully restore youthful accommodative ability after cataract surgery.

Advisor: Ryan M. Pedrigi