Finite Element Simulation and Experimental Test of Ovine Corneal Tissue Cutting Process in Cataract Surgery Operation

The modeling of corneal tissue cutting is essential in developing haptic training simulators and robot-assisted surgeries. A finite element model was developed for the ovine corneal cutting process and validated with an experimental setup for the first time. The experimental setup measured force in pre-cutting, cutting, and relaxation phases. The mechanical behavior of corneal incision was modeled by the finite element method. A test setup was built to conduct experiments on ۳۲ fresh and well-preserved ovine cornea. Force was recorded with the sampling rate of ۲۰۰ Hz. The tests were performed for intraocular pressures from ۱۵ mm-Hg to ۱۸ mm-Hg, and keratome velocities of ۱ mm/s and ۲ mm/s. The finite element model characterized the nonlinear behavior of the ovine corneal tissue. In the pre-cutting phase, force increased until the instrument tip penetrated. A ۱۲.۳% (۲ mm/s) and ۱۹.۱% (۱ mm/s) reduction in force indicated the onset of the cutting phase after which force remained constant. At the relaxation phase, force returned to zero. The cutting force values varied by pressure between ۰.۱۸۳N and ۰.۲۸۷ N for ۱ mm/s and between ۰.۲۱۱ N and ۰.۲۸۱ N for ۲ mm/s of keratome velocity, respectively. The finite element simulations show that the maximum force errors predicted by the model is ۰.۰۴۲ N for ۲ mm/s of keratome velocity. The root mean square of force error between the finite element simulations and the experiments is ۰.۰۲۵ N.

Keywords:

Finite element model , Corneal Cutting Force , Soft Tissue Damage Model , Corneal Surgery Modeling , Needle Insertion