Determining optimal ultrasound off time with micropulse longitudinal phacoemulsification
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Published on: January 26, 2018
Jason D Jensen1, Kevin R Kirk1, Isha Gupta1
1From the Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.
Purpose:
To evaluate the optimum off time for the most efficient removal of lens fragments using micropulse ultrasound (US).
Setting:
John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, USA.
Design:
Experimental study.
Methods:
Porcine lens nuclei were soaked in formalin for 2 hours and then cut into 2.0 mm cubes using the Signature US machine with a bent 0.9 mm phaco tip with a 30-degree bevel. The on time was 7 milliseconds (ms), and the off time was varied from 2 to 20 ms in 2 ms steps. Phacoemulsification efficiency (time for fragment removal) and chatter (number of times the fragment bounced from the tip) were measured.
Results:
A nonsignificant linear increase in efficiency was observed with 2 to 6 ms of off time (R(2) = .87, P = .24). A significant linear decrease in efficiency was observed with 6 to 20 ms (R(2) = .74, P = .006).
Conclusions:
With micropulse longitudinal US, 6 to 7 ms of off time was as efficient as shorter off times; longer off times (8 to 20 ms) showed decreased efficiency. Chatter was minimal and statistically similar throughout. To maximize phacoemulsification US efficiency, an off-time setting of 6 ms is recommended.
Financial Disclosure:
No author has a financial or proprietary interest in any material or method mentioned.
