Authors
Graf, T., Gisler, T., Emmenegger, S., Tanner, S., Menapace, R., Di Nardo, S.
Abstract
Abstract Objective: A comprehensive technical and biomedical analysis of ultrasound-induced effects during phacoemulsification cataract surgery (PCS) and an assessment of the potential risks associated with ultrasound emulsification. Methods: Modeling ultrasound wave propagation and intensities using the finite element method (FEM). Cavitation onset was experimentally validated in a pressure chamber observed with a high-speed camera. The thermal effects of ultrasound energy were estimated through established physical and thermal models and confirmed in a cuvette setup using thermistor probes. Results: At the distal end of the PCS tip, the ultrasound wave intensity reached 0.2 W/mm2, resulting in ocular tissue displacements in the anterior chamber below 2 m. The temperature rise in the anterior chamber was less than 0.2 {degrees}C/s. Both observations indicate negligible mechanical and thermal risk to ocular tissues. High-speed imaging confirmed cavitation confined to the tip region. Emulsification efficacy was maintained even under conditions that suppressed cavitation, including elevated ambient pressures and cavitation-inhibiting fluids. Results indicate that mechanical fragmentation by tip oscillation (jackhammer effect) is the only relevant emulsification mechanism, while cavitation plays a negligible role. Acoustic streaming was observed during ultrasound excitation without phaco sleeve. During phacoemulsification, the sleeve suppressed acoustic streaming into the anterior chamber. Conclusions: The findings validate the safety of ultrasound-based PCS and confirm that tissue fragmentation is primarily driven by the oscillating tip direct action.
Preprint server:
bioRxiv
The authors list and abstract were imported from bioRxiv on 02 Nov 2025.
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