Impact Of A Novel Volumetric Ultrasound Modality On Phacoemulsification Tip Efficiency, Fluidics, Cavitation And Thermal Profile

To compare lens emulsification efficiency, fluid streaming, cavitation behavior, acoustic profile, and thermal characteristics of Hybrid and Balanced phaco tips using Volumetric (UNITY 4D Phaco), torsional (Ozil), and axial ultrasound modes. We hypothesized that volumetric motion would improve efficiency in dense lens material while preserving favorable fluidics and thermal safety compared with torsional and longitudinal ultrasound.

Phaco-Dynamics Laboratory, Pasteur Ophthalmic Clinic, Santiago, Chile

Chemically modified porcine lenses were graded and emulsified using volumetric, torsional, and axial modes with Hybrid and Balanced tips. Emulsification speed was recorded at comparable ultrasonic power. High-speed videography and stroboscopic illumination characterized distal tip kinematics and tip–tissue interaction. Particle image velocimetry evaluated streaming patterns. Optical cavitation was assessed by high-speed imaging, acoustic cavitation by directional hydrophone, and incision temperature rise by FLIR thermography under standardized 30 cc/min flow conditions.

Volumetric ultrasound generated a multidimensional distal tip trajectory combining axial, lateral, and vertical components, distinct from torsional and axial modes. Alternating-mode experiments demonstrated greater emulsification efficiency during volumetric activation. Axial mode produced retrograde streaming opposing aspiration and the highest optical and acoustic cavitation with the greatest thermal rise. Torsional and volumetric aligned streaming with aspiration. Volumetric showed moderated cavitation and incision temperatures comparable to torsional for both tip designs.

Volumetric phacoemulsification exhibits a true multidimensional motion pattern translating into superior emulsification efficiency while maintaining favorable streaming direction, controlled cavitation, and thermal behavior comparable to torsional ultrasound. Across Hybrid and Balanced designs, volumetric motion combines cutting efficiency with improved fluidic stability and reduced adverse effects seen with axial ultrasound, supporting its role as a distinct and clinically advantageous modality.