Effect of Micropulsed Ultrasound Power on Efficiency and Chatter

Zaugg, Brian

Effect of Micropulsed Ultrasound Power on Efficiency and Chatter

Tuesday, April 21, 2015: 1:26 PM

Room 4 (San Diego Convention Center)

Brian E. Zaugg, MD

Kevin Garff

Judd M. Cahoon, PhD

Jason D. Jensen

Isha Gupta, BS

Gareth Lance Gardiner, BS

Brian C. Stagg, MD

William R. Barlow, MD

Jeff H. Pettey, MD

Randall J. Olson, MD

Purpose
To determine the optimal power settings in micropulsed ultrasound.

Methods
Pig lenses hardened in a manner comparable to dense human cataracts were cut into 2mm cubes and removed with micropulsed longitudinal ultrasound using previously optimized settings (6ms on and 6ms off using 0.9mm bent phaco with 30 degree bevel). Aspiration was set to 40ml/min and vacuum to 550mmHg. 20 lens cubes were tested with power at 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%. Primary outcome measures were efficiency time (time in seconds to lens removal) and chatter (number of times the lens fragment visibly bounced off the phaco tip).

Results
Efficiency time improved with increasing power. There was a correlation between power and efficiency time (R² = .41, P = .046, ANOVA) which was more substantial between 20% to 100% power (R² = .71, P = .004, ANOVA). There was no significant relationship between power and chatter (R² = .0671, P = .47).

Conclusion
We found a large (5-fold) increase in efficiency between 10% and 20% power, which likely indicates that a minimum threshold of power is necessary in order to cause efficient breakup of the lens. Between 20% and 100% power, there was a linear, strong (R² = .71), and statistically significant improvement in efficiency. Additionally, micropulsed ultrasound exhibited little chatter and microchatter throughout the entire power range.