Numerical modelling to assess the tear force of human capsulotomy margin

Tear force of the capsulotomy edge is a paramount parameter to affect the surgical safety in cataract surgery. This paper aimed to investigate the stretch force of the capsulotomy edge using finite element (FE) method. A FE model of capsule bag was developed to simulate dynamic response of the lens capsule to the stretch of retractors. The failure criterion based on the distortion energy theory was applied to predict the rupture of the anterior capsule. The simulation results showed a good agreement with the experimental data reported in the literature. Sensitivity studies were then conducted to evaluate the effect of the various parameters on tear force, including the stretching velocity, capsulorhexis dimension, age, retractor width and shape, and rim morphology. The rupture force was proportional to the stretching velocity, capsulorhexis dimension and retractor width, while the age showed the opposite trend. In addition, the retractor shape has a greatly effect on the tear force and the rim of continuous curvilinear capsulorhexis (CCC) has the higher tear resistance. This work can contribute to the understanding of the regularity for capsule rupture.