title: Effect of cutting phases on flow rate in 20-, 23-, and 25-gauge vitreous cutters.
abstract: BACKGROUND
  Vitrectomy systems are now available with 20-, 23-, and 25-gauge vitreous cutters and are designed to be used with conventional or new generation pneumatic actuation technology.
  
  
  METHODS
  Five vitreous cutters using pneumatic actuation technology were studied. Flow rates were evaluated using porcine vitreous. A high-speed camera timed the cutting phases (open, closing, closed, and opening), and duty cycle was calculated. The cutting port surface area and internal shaft surface areas were calculated.
  
  
  RESULTS
  Increasing cut rate decreased the average open phase duration without affecting other cutting phases. The opening and closing phases of vitreous cutters using new generation pneumatic actuation technology were longer than those for other vitreous cutters. Flow rate was correlated to internal shaft surface area.
  
  
  CONCLUSIONS
  In addition to confirming the importance of duty cycle at high cut rates, this study demonstrated that the transition phases should also be considered when one is evaluating the efficiency of a vitreous cutter.
authors.affiliation: Jules Stein Eye Institute, Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, California, USA. hubschman@jsei.ucla.edu
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Hubschman
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Bourges
authors.forename: Irena
authors.initials: I
authors.lastname: Tsui
authors.forename: Shantan
authors.initials: S
authors.lastname: Reddy
authors.forename: Fei
authors.initials: F
authors.lastname: Yu
authors.forename: Steven D
authors.initials: SD
authors.lastname: Schwartz
mesh_terms: D000818:Animals; D008866:Microsurgery / Q000295:instrumentation*; D013396:Suction; D013552:Swine; D014618:Vacuum; D014821:Vitrectomy / Q000295:instrumentation*; D014822:Vitreous Body / Q000601:surgery*