title: Impact of micropulsed ultrasound power settings on the efficiency and chatter associated with lens-fragment removal.
abstract: OBJECTIVE
  To determine the optimum power settings in micropulsed ultrasound (US).
  
  
  METHODS
  John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, USA.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  Pig lenses hardened to be comparable to dense human cataracts were cut into 2.0 mm cubes and removed using micropulsed longitudinal US with previously optimized settings (6 milliseconds on and 6 milliseconds off and using a 0.9 mm 30-degree beveled bent phaco tip). The aspiration was set at 40 mL/min and the vacuum level at 550 mm Hg. Twenty lens cubes were tested with the power set from 10% to 100% in increments of 10%. Primary outcome measures were efficiency time (time to lens removal) and chatter (number of times the lens fragment visibly bounced off the tip).
  
  
  RESULTS
  Efficiency time decreased with increasing power. There was a correlation between power and efficiency time (R(2) = 0.41, P = .046), which was more substantial between 30% and 100% power (R(2) = 0.71, P = .004). The mean number of chatter events did not differ significantly between power settings (R(2) = 0.012, P = .1195).
  
  
  CONCLUSIONS
  There was a 5-fold increase in efficiency between 10% power and 20% power, which likely indicates that there is a minimum power threshold for efficient breakup of the lens. Between 20% and 100% power, there was a linear, strong, and statistically significant improvement in efficiency in these lens fragments. In addition, with micropulsed US there was little chatter or microchatter throughout the power range.
  
  
  BACKGROUND
  No author has a financial or proprietary interest in any material or method mentioned.
authors.affiliation: From the Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Garff
authors.affiliation: From the Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Jason D
authors.initials: JD
authors.lastname: Jensen
authors.affiliation: From the Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Judd
authors.initials: J
authors.lastname: Cahoon
authors.affiliation: From the Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Isha
authors.initials: I
authors.lastname: Gupta
authors.affiliation: From the Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Stagg
authors.affiliation: From the Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Brian E
authors.initials: BE
authors.lastname: Zaugg
authors.affiliation: From the Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.
authors.forename: William R
authors.initials: WR
authors.lastname: Barlow
authors.affiliation: From the Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. Electronic address: randallj.olson@hsc.utah.edu.
authors.forename: Randall J
authors.initials: RJ
authors.lastname: Olson
mesh_terms: D000818:Animals; D019220:High-Energy Shock Waves; D007908:Lens, Crystalline / Q000601:surgery*; D061646:Operative Time; D018918:Phacoemulsification / Q000295:instrumentation*; D013552:Swine; D014465:Ultrasonics / Q000592:standards*