Effect of high vacuum and aspiration on phacoemulsification efficiency and chatter using a transversal ultrasound machine.

Purpose: To examine the role of high vacuum and aspiration settings on efficiency using a transversal ultrasound (US) machine.

Setting: John A. Moran Eye Center Laboratory, University of Utah, Salt Lake City, Utah, USA.

Design: Experimental study.

Methods: Porcine lens nuclei were incubated in formalin for 2 hours and then cut into 2.0 mm cubes. Phacoemulsification was performed using the Whitestar Signature machine. Settings were bottle height 50 cm, on-time 6 milliseconds, and off-time 6 milliseconds. One hundred percent power was used for all 240 runs. Tested parameters were aspiration of 50 mL/min and 60 mL/min and vacuum of 500, mm Hg, 600 mm Hg, and 650 mm Hg.

Results: With continuous US, increasing aspiration from 50 mL/min to 60 mL/min significantly increased efficiency (23%). Increasing vacuum from 500 mm Hg to 650 mm Hg and from 600 mm Hg to 650 mm Hg significantly increased efficiency (20.2% and 13.6%, respectively). Higher vacuum and aspiration parameters did not influence the incidence of chatter events. In the micropulse US group, there was no significant efficiency increase with increasing vacuum or aspiration levels. There was a significant efficiency increase of continuous over micropulse US at an aspiration setting of 60 mL/min and vacuum settings of 600 mm Hg and 650 mm Hg.

Conclusions: As aspiration and vacuum increased, efficiency increased under continuous transverse US. No significant efficiency improvement occurred at high aspiration and vacuum settings under micropulse US. At 60 mL/min aspiration and more than 600 mm Hg vacuum, continuous power was significantly more efficient than micropulse transverse US.