PNNL

Abstract

Phacoemulsification is a highly effective and commonly used procedure and yet the fundamental physics for the mechanics that occur in the tissue disruption remains the subject of significant debate. Ultrasonic surgery units operating in the frequency range 20-60 kHz for tissue fragmentation and removal have been available for about 30 years. Such devices are widely used in phacoemulsification, a range of other procedures that include the recanalization of coronary arteries, and in various soft tissue procedures, particularly neurosurgery [1]. Studies of such procedures are reported in well over 100 papers, mostly in clinical journals that focus on outcomes while little attention is focused on the tissue disruption mechanisms. In all these types of procedures using such instruments where a hard vibrating tip is used to cut or shatter hard tissue or to cut or emulsify soft tissues [2], the fundamental physics of the interaction is the same. In surgical practice, if a flat ended tube is employed, the tip is commonly set at an angle to the surface to ?machine away? tissue. In phacoemulsification, a variety of beveled tips are employed to achieve the same effect [3]. The use of non-normal incidence and the beveled tip significantly increases the range of tough tissues which can be fragmented and lowers the power (amplitude) at which cutting is initiated for a particular tissue. But the question still remains ? what is the mechanism or mechanisms that so effectively disrupt the tissue?