title: Force comparison of air currents produced by a standard and modified infusion cannula.
abstract: OBJECTIVE
  To develop and characterize an infusion cannula that reduces the intraocular jet forces created during fluid-air exchange.
  
  
  METHODS
  A new infusion cannula was manufactured by adding a baffle 1.0 mm perpendicular to the distal opening of a 20-gauge infusion. The forces generated by the modified and standard cannulas were measured at a constant air infusion pressure of 50 mmHg by using a force sensor coupled to a schematic eye with eight radial positions from 0 degrees to 180 degrees along the circumference. Five different orientations relative to the baffle support of the modified cannula were evaluated at each position to assess the turbulent flow.
  
  
  RESULTS
  The standard cannula produced a maximum force of 0.14 mmHg at 180 degrees from the sensor. The modified cannula generated a maximum pressure of 0.017 mmHg at 67.5 degrees from the sensor. Overall, the force from the modified cannula was an order of magnitude less than the standard infusion cannula (P < 0.01).
  
  
  CONCLUSIONS
  The modifications of the new infusion cannula are passive with respect to its surgical performance. However, the additional baffle transforms laminar air currents into turbulent ones and allows dispersion of the jet forces, which should reduce barotrauma and desiccation of the retina during fluid-air exchange.
authors.affiliation: Microsurgery Advanced Design Laboratory, Doheny Retina Institute at Doheny Eye Institute, The Keck School of Medicine, University of Southern California, Los Angeles, USA.
authors.forename: Byron S
authors.initials: BS
authors.lastname: Ladd
authors.forename: Gildo Y
authors.initials: GY
authors.lastname: Fujii
authors.forename: Puneet
authors.initials: P
authors.lastname: Gupta
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Jensen
authors.forename: Anthony
authors.initials: A
authors.lastname: Kouzis
authors.forename: Juliana V
authors.initials: JV
authors.lastname: Rossi
authors.forename: Aaron
authors.initials: A
authors.lastname: Barnes
authors.forename: Eugene
authors.initials: E
authors.lastname: De Juan
mesh_terms: D001696:Biomechanical Phenomena; D002404:Catheterization / Q000295:instrumentation*; D006801:Humans; D007431:Intraoperative Complications / Q000517:prevention & control; D008954:Models, Biological; D013508:Ophthalmologic Surgical Procedures / Q000295:instrumentation*; D011312:Pressure