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Updated: Jun 18, 2026
Studying Cavitation Enhanced Therapy
Published on: April 9, 2021
Ultrasound phacoemulsification: physical mechanisms, cavitation, and thermal effects
Thomas Graf1, Thomas Gisler, Silvio Emmenegger
1From the Lucerne University of Applied Sciences and Arts, Institute of Electrical Engineering, Horw, Switzerland (Graf, Gisler, Emmenegger); Lucerne University of Applied Sciences and Arts, Institute of Medical Engineering, Horw, Switzerland (Tanner, Di Nardo); Department of Ophthalmology, Medical University of Vienna, Vienna, Austria (Menapace).
Purpose:
To perform a comprehensive technical and biomedical analysis of ultrasound-induced effects during phacoemulsification cataract surgery (PCS) and assess the potential risks associated with ultrasound emulsification.
Setting:
Lucerne University of Applied Sciences and Arts, Horw, Switzerland.
Design:
Computational modeling and laboratory bench testing.
Methods:
Ultrasound wave propagation and intensity were simulated using the finite element method. The onset of cavitation was experimentally validated in a pressure chamber and observed using a high-speed camera. The thermal effects of ultrasound energy were estimated using 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/mm 2 , resulting in ocular tissue displacements in the anterior chamber below 2 μm. The temperature rise in the anterior chamber was less than 0.2°C/s. Both observations indicate negligible mechanical and thermal risks to ocular tissues. High-speed imaging confirmed that cavitation was confined to the PCS tip region. The efficiency of emulsification was maintained even under conditions that suppressed cavitation, including elevated ambient pressures and cavitation-inhibiting fluids. The results indicate that mechanical fragmentation by tip oscillation ("jackhammer effect") is the only relevant emulsification mechanism, whereas cavitation plays a negligible role. Acoustic streaming was observed during the ultrasound excitation without a phacoemulsification sleeve. During phacoemulsification, the sleeve suppresses acoustic streaming into the anterior chamber.
Conclusions:
These findings validate the safety of ultrasound-based PCS and confirm that lens fragmentation is primarily driven by the direct action of the oscillating tip.
