Efficiency of Micropulse On-Time Duty Cycle Settings

Pettey, Jeff

Efficiency of Micropulse On-Time Duty Cycle Settings

Sunday, April 27, 2014: 8:45 AM

Room 151A (Boston Convention and Exhibition Center)

Jeff H. Pettey, MD, Moran Eye Center, Univeristy of Utah, Salt Lake City, UT, USA

Randall J. Olson, MD, Univ. of Utah, Dept of Ophth, Salt Lake City, UT, USA

William R. Barlow, MD, University of Utah, Salt Lake City, UT, USA

Brian E. Zaugg, MD, University of Utah John A Moran Eye Center, North Salt Lake, Utah, USA

Brian C. Stagg, MD, Moran Eye Center, Salt Lake City, UT, USA

Kevin Kirk, University of Utah, Salt Lake City, UT, USA

Cecinio Ronquillo Jr., PhD, John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA

Jason D. Jensen, University of Utah, Salt Lake City, UT, USA

Mohammed A. Farukhi SLC, UT, USA

Isha Gupta, University of Utah School of Medicine, Salt Lake City, UT, USA

Narrative Responses:

Purpose
To evaluate the optimal on time for the most efficient removal of lens fragments using micropulsed ultrasound.

Methods
Porcine lens nuclei were formalin-soaked for two hours, then divided into 2mm cubes. Using an ultrasound machine with a 0.9mm bent, 30 degree bevel tip, the on time was varied every millisecond (ms) from 2ms - 10 ms with the off time kept constant at 10ms. Efficiency (time to lens removal) and chatter (number of lens fragment repulsions from the tip) were determined.

Results
The most efficient phacoemulsification was achieved with an on time of 6ms for an off time of 10 ms. Times shorter than 6ms were significantly less efficient (R2 = .82, P = .04) while times greater than 6ms did not result in a significant change in efficiency (R2 =.03, P = .78). Times between 9 and 10 ms had more chatter events compared to the 2-8ms groups(P < .0001).

Conclusion
With micropulsed longitudinal ultrasound 6ms on time was equally as efficient as longer on times, while shorter on times (2-5ms) had decreased efficiency. At 9 and 10ms on there was significantly more chatter noted. Therefore, in order to maximize phacoemulsification, we recommend an on time setting of 6ms.