The rhexis for many surgeons is the most challenging step in phacoemulsification.  The anterior capsule is approximately 12 microns in thickness and subject to radial forces from the zonules as well as anterior pressure from the viscoelastic and posteriorly from the lens. The dynamics change as the capsulotomy needle pierces the capsule and the rhexis is propagated using the Utrata forceps.  These vector forces must be controlled to perform a continuous curvilinear capsulorrhexis (CCC).  There is a tendency for the forces to pull the rhexis towards the zonules risking posterior capsule damage and nucleus dislocation.