title: Determining optimal torsional ultrasound power for cataract surgery with automatic longitudinal pulses at maximum vacuum ex vivo.
abstract: OBJECTIVE
  To determine the optimal longitudinal power settings for Infiniti OZil Intelligent Phaco (IP) at varying torsional amplitude settings; and to test the hypothesis that increasing longitudinal power is more important at lower torsional amplitudes to achieve efficient phacoemulsification.
  
  
  METHODS
  Laboratory investigation.
  
  
  METHODS
  setting: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah. procedure: Individual porcine nuclei were fixed in formalin, then cut into 2.0 mm cubes. Lens cube phacoemulsification was done using OZil IP at 60%, 80%, and 100% torsional amplitude with 0%, 10%, 20%, 30%, 50%, 75%, or 100% longitudinal power. All experiments were done using a 20 gauge 0.9 mm bent reverse bevel phaco tip at constant vacuum (550 mm Hg), aspiration rate (40 mL/min), and bottle height (50 cm). main outcome measure: Complete lens particle phacoemulsification (efficiency).
  
  
  RESULTS
  Linear regression analysis showed a significant increase in efficiency with increasing longitudinal power at 60% torsional amplitude (R(2) = 0.7269, P = .01) and 80% torsional amplitude (R(2) = 0.6995, P = .02) but not at 100% amplitude (R(2) = 0.3053, P = .2). Baseline comparison of 60% or 80% vs 100% torsional amplitude without longitudinal power showed increased efficiency at 100% (P = .0004). Increasing longitudinal power to 20% abolished the efficiency difference between 80% vs 100% amplitudes. In contrast, 75% longitudinal power abolished the efficiency difference between 60% vs 100% torsional amplitudes.
  
  
  CONCLUSIONS
  Results suggest that longitudinal power becomes more critical at increasing phacoemulsification efficiencies at torsional amplitudes less than 100%. Increasing longitudinal power does not further increase efficiency at maximal torsional amplitudes.
authors.affiliation: Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah.
authors.forename: Cecinio C
authors.initials: CC
authors.lastname: Ronquillo
authors.affiliation: Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah.
authors.forename: Brian
authors.initials: B
authors.lastname: Zaugg
authors.affiliation: Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah.
authors.forename: Brian
authors.initials: B
authors.lastname: Stagg
authors.affiliation: Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah.
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Kirk
authors.affiliation: Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah.
authors.forename: Isha
authors.initials: I
authors.lastname: Gupta
authors.affiliation: Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah.
authors.forename: William R
authors.initials: WR
authors.lastname: Barlow
authors.affiliation: Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah.
authors.forename: Jeff H
authors.initials: JH
authors.lastname: Pettey
authors.affiliation: Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah. 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*; D018918:Phacoemulsification / Q000295:instrumentation*; D013010:Sonication; D013552:Swine; D054159:Torsion, Mechanical; D014463:Ultrasonography; D014618:Vacuum