3 years ago

Determining optimal ultrasound percent on time with long-pulse torsional phacoemulsification

Sami W. Kabbara, Joshua Heczko, Brian Ta, Ashlie Bernhisel, William Barlow, Brian Zaugg, Randall J. Olson, Jeff Pettey

Publication date: Available online 11 September 2018

Source: Canadian Journal of Ophthalmology

Author(s): Sami W. Kabbara, Joshua Heczko, Brian Ta, Ashlie Bernhisel, William Barlow, Brian Zaugg, Randall J. Olson, Jeff Pettey


To evaluate the optimum percent on time for the most efficient lens fragment removal using long-pulse torsional ultrasound (US).


In vitro laboratory study.


Porcine lens nuclei were incubated in formalin for 2 hours and then cut into 2 mm cubes. Phacoemulsification was performed using the Centurion® Vision System and Infiniti OZil handpiece with the balanced tip. Vacuum was set at 500 mm Hg, aspiration rate at 50 mL/min, and intraocular pressure (IOP) at 50 mm Hg. Pulse rate was 26 pulses/second. Studied parameters were percent power: 60%, 80%, and 100%, and percent on times: 50%, 60%, 70%, and 80%. Efficiency was the total time for a cube to be emulsified. Chatter was the number of times the lens fragment bounced off the tip.


There was no significant difference in efficiency between 50%, 60%, and 70 % on-time settings (p = 0.17 and 0.08, respectively); however, there was significant increase in efficiency when the on time was increased from 70% to 80% (p = 0.03). Increasing power from 60% to 100% showed a statistically significant efficiency increase (p = 0.001). There was no significant change in chatter with increasing on time; however, there was a statistically significant increase in chatter with every power level increase.


Increasing on-time percent does not improve efficiency under torsional long-pulse US. There is no significant change in chatter with increasing on-time percent. Increasing power increases efficiency despite chatter increase. Long-pulse US does not appear to influence torsional action in a clinically meaningful way.

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