title: Experimental anterior chamber maintenance in active versus passive phacoemulsification fluidics systems.
abstract: OBJECTIVE
  To evaluate the ability of phacoemulsifiers with active versus passive infusion fluidics control systems to maintain target intraocular pressures (IOPs) under varying flow conditions.
  
  
  METHODS
  Alcon Research, Ltd., Lake Forest, California, USA.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  An acrylic test chamber was used to model the anterior chamber of the eye. Two passive (gravity-based) systems were tested using bottle heights yielding infusion pressures of 41, 75, and 109 cm of water under zero-flow conditions. One actively controlled system was tested using equivalent target IOPs of 30, 55, and 80 mm Hg. Test chamber IOPs were measured at aspiration flow rates of 15, 30, 45, and 60 cc/min.
  
  
  RESULTS
  The measured flow rates were similar between fluidics systems across the range of intended aspiration flow rates. All systems achieved the desired target IOPs under zero-flow conditions. After activation of aspiration flow, however, measured IOPs decreased from target IOPs for the 2 passive systems. Each 15 cc/min increase in the aspiration flow rate produced a pressure drop of 14.0 to 16.2 mm Hg or 9.3 to 14.2 mm Hg, depending on the system. Measured IOPs in the actively controlled system closely matched the targeted IOPs across all tested aspiration flow rates, deviating from targets by no more than 4.3 mm Hg.
  
  
  CONCLUSIONS
  All phacoemulsification aspiration infusion fluidics systems achieved target IOPs under zero-flow conditions. Only the actively controlled system maintained target IOPs across a range of aspiration flow rates. These experimental findings suggest that anterior chamber stability might be better in the clinical setting using an actively controlled system.
  
  
  BACKGROUND
  Dr. Dimalanta is an employee of Alcon Research, Ltd. Dr. Miller is an investigator and speaker for and a consultant to Alcon Laboratories, Inc. Dr. Nicoli has no financial or proprietary interest in any material or method mentioned.
authors.affiliation: From the Jules Stein Eye Institute and Department of Ophthalmology (Nicoli, Miller), David Geffen School of Medicine, University of California, Los Angeles, and Alcon Research, Ltd. (Dimalanta), Lake Forest, California, USA.
authors.forename: C Manuel
authors.initials: CM
authors.lastname: Nicoli
authors.affiliation: From the Jules Stein Eye Institute and Department of Ophthalmology (Nicoli, Miller), David Geffen School of Medicine, University of California, Los Angeles, and Alcon Research, Ltd. (Dimalanta), Lake Forest, California, USA.
authors.forename: Ramon
authors.initials: R
authors.lastname: Dimalanta
authors.affiliation: From the Jules Stein Eye Institute and Department of Ophthalmology (Nicoli, Miller), David Geffen School of Medicine, University of California, Los Angeles, and Alcon Research, Ltd. (Dimalanta), Lake Forest, California, USA. Electronic address: miller@jsei.ucla.edu.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Miller
mesh_terms: D000085:Acetates / Q000008:administration & dosage*; D000867:Anterior Chamber / Q000033:anatomy & histology*; D003187:Compliance; D004338:Drug Combinations; D006801:Humans; D057446:Hydrodynamics; D007429:Intraocular Pressure / Q000502:physiology*; D008903:Minerals / Q000008:administration & dosage*; D009883:Ophthalmic Solutions / Q000008:administration & dosage*; D018918:Phacoemulsification; D012965:Sodium Chloride / Q000008:administration & dosage*; D013396:Suction
chemical_list: D000085:Acetates; C030660:BSS solution; D004338:Drug Combinations; D008903:Minerals; D009883:Ophthalmic Solutions; D012965:Sodium Chloride