title: Bead-flow pattern: quantitation of fluid movement during torsional and longitudinal phacoemulsification.
abstract: OBJECTIVE
  To develop a bead-flow pattern for visualizing and comparatively quantifying fluid movement using a torsional or longitudinal ultrasound (US) phaco handpiece.
  
  
  METHODS
  Magill Laser Center, Medical University of South Carolina, Charleston, South Carolina, USA.
  
  
  METHODS
  Visualization and quantification of intraocular fluid dynamics were evaluated by injecting neutrally buoyant, collagen-coated polystyrene beads (diameter, 125 to 212 microm) into the phacoemulsification irrigation flow. Using the anterior chamber of a cadaver or porcine eye or a laboratory test chamber, the bead-flow pattern was video recorded. Qualitative comparisons between longitudinal and torsional phacoemulsification were made using video-processing software to track the beads frame by frame. The time (quantitative) required to aspirate a bolus of beads from the anterior chamber (clearance time) was measured and compared between the 2 modalities. Aspiration efficiency was calculated to compare operating conditions in a test chamber using high-speed videography; conditions included irrigation/aspiration (I/A) only (0% power) and clinically relevant fluidic parameters and power modulations with torsional, longitudinal, or a combination of powers applied.
  
  
  RESULTS
  Qualitative and quantitative analyses of the fluidic patterns of bead flow in the peripheral anterior chamber and near the aspirating tip opening indicated that torsional fluidics behave closer to the I/A-only configuration than longitudinal phacoemulsification, with the latter repelling more bead material in front of the aspiration tip. Bead clearance time was approximately 50% faster with torsional than with longitudinal US, regardless of the power setting.
  
  
  CONCLUSIONS
  Bead flow-pattern evaluation is a feasible approach to future studies of fluid movement in the anterior chamber.
authors.affiliation: Magill Research Center for Vision Correction, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina 29425, USA. decastro@musc.edu
authors.forename: Luis E Fernández
authors.initials: LE
authors.lastname: de Castro
authors.forename: Ramon C
authors.initials: RC
authors.lastname: Dimalanta
authors.forename: Kerry D
authors.initials: KD
authors.lastname: Solomon
mesh_terms: D000818:Animals; D000867:Anterior Chamber / Q000378:metabolism*; D020099:Coated Materials, Biocompatible; D006801:Humans; D008863:Microspheres; D009883:Ophthalmic Solutions / Q000378:metabolism*; D018918:Phacoemulsification / Q000379:methods*; D013396:Suction; D013552:Swine; D054159:Torsion, Mechanical; D014741:Video Recording
chemical_list: D020099:Coated Materials, Biocompatible; D009883:Ophthalmic Solutions