title: Introducing new vitreous cutter blade shapes: a fluid dynamics study.
abstract: OBJECTIVE
  To assess the efficacy of novel vitreous cutter blades compared with the regular guillotine by means of particle image velocimetry. Tested blades included a regular blade (RB) and newer designs where a circular (hole blade [HB]) or a slit aperture (slit blade [SB]) had been opened proximal to the cutting edge.
  
  
  METHODS
  Twenty-three-gauge probes were immersed in BSS or egg albumen, and high-speed video (1,000 frames per second) was recorded. Duty cycle, flow rate, and acceleration generated by Venturi and peristaltic pumps were measured under cutter settings simulating "low-speed" vitrectomy (1600 cuts per minute, 200 mmHg vacuum) and "high speed" vitrectomy (3000 cuts per minute, 300 mmHg vacuum).
  
  
  RESULTS
  The SB and HB had a significantly more favorable duty cycle than that of the RB (P < 0.01) and higher BSS flow rate regardless of the aspiration. The SB flow rate in albumen was significantly higher than that of the HB and RB only over 1,000 cuts per minute using a peristaltic pump and at any cut rate with Venturi pump (P < 0.001). The SB also yielded the lowest fluid acceleration than both the HB and SB (P < 0.001 in all cases).
  
  
  CONCLUSIONS
  The HB and SB proved to be significantly more efficient than the RB, with better duty cycle and higher flow rate. The SB generated significantly less fluid acceleration than any other tested blade, regardless of the fluid viscosity and pump technology. The SB design is significantly more efficient and possibly safer than both HB and RB.
authors.affiliation: *Eye Hospital of Rome, University of Cagliari, Cagliari, Italy, FAculty of Engineering, DICAT Department, Bietti Foundation IRCCS, Rome, Italy, Optikon 2000 Inc, Rome, Italy; †University of Cagliari, DICAAR; ‡Optikon 2000 Inc; and §Fondazione G.B. Bietti, IRCCS.
authors.forename: Tommaso
authors.initials: T
authors.lastname: Rossi
authors.forename: Giorgio
authors.initials: G
authors.lastname: Querzoli
authors.forename: Giampiero
authors.initials: G
authors.lastname: Angelini
authors.forename: Carlo
authors.initials: C
authors.lastname: Malvasi
authors.forename: Mario
authors.initials: M
authors.lastname: Iossa
authors.forename: Luca
authors.initials: L
authors.lastname: Placentino
authors.forename: Guido
authors.initials: G
authors.lastname: Ripandelli
mesh_terms: D000085:Acetates; D004338:Drug Combinations; D004867:Equipment Design; D006801:Humans; D057446:Hydrodynamics; D008903:Minerals; D010047:Ovalbumin; D012965:Sodium Chloride; D014741:Video Recording; D014821:Vitrectomy / Q000295:instrumentation*; D014822:Vitreous Body / Q000601:surgery*
chemical_list: D000085:Acetates; C030660:BSS solution; D004338:Drug Combinations; D008903:Minerals; D012965:Sodium Chloride; D010047:Ovalbumin