1. A phacoemulsification procedure, comprising: (a) forming at least one opening in the eye to provide access to the anterior portion of the lens capsule; (b) forming an opening in the anterior region of a lens capsule containing a lens to be removed; (c) inserting a working end of a phacoemulsification instrument through the opening in the anterior region of the lens capsule; (d) obtaining diagnostic scan data for the lens, the posterior portion of the capsule and the working end of the phacoemulsification instrument; (e) analyzing the diagnostic scan data to obtain a separation distance between the working end of the phacoemulsification instrument and the posterior region of the capsule; (f) operating the phacoemulsification instrument while viewing the lens and the working end of the phacoemulsification instrument and while receiving separation distance information from the analysis of the diagnostic scan data and using the separation distance information in the control of the operation of the instrument; wherein during the course of the procedure, the diagnostic scan data, the analysis of the data, and the receiving of the separation distance information are updated a plurality of times.