Quantifying Phacoemulsification Handpiece Repulsion as a Function of Tip Design: A Particle Image Velocimetry Study

The aim of this study was to compare the fluidics of different phaco tip designs: straight, flared, and balanced, across 2 orthogonal planes centred on the tip aperture, with the aim of inferring lens fragment attraction and repulsion determined by shear fluid motion.

Phaco handpiece of Virtuoso (BVI) longitudinally drove straight and flared tips, while Centurion (Alcon) drove balanced tip in longitudinal, torsional, and combined modes. Tests were run into a Plexiglas chamber filled with balanced salt solution with neutrally buoyant particles, and particle image velocimetry analysis was performed at 6,250 frames per second.

BSS velocity increased with stroke length and was significantly higher for the balanced tip longitudinal stroke (p < 0.01). At 90% ultrasound power, the balanced tip generated significantly higher BSS velocities than the straight and flared tips, both in longitudinal, purely torsional, and combined motion (p < 0.05). Aspiration significantly altered BSS velocities in all tested tips (p < 0.05 for all), increasing attraction. Straight tips showed the lowest BSS velocity at all stroke lengths (p < 0.01); balanced tip in torsional mode had the second highest BSS velocity (after the same tip in longitudinal mode) across the vertical plane.

Straight tips in longitudinal mode determine significantly lower fluid velocity in a test chamber than flared and balanced tips operating in longitudinal, torsional, and combined modes.