title: Improvement in outflow facility by two novel microinvasive glaucoma surgery implants.
abstract: OBJECTIVE
  To determine improvement in outflow facility (C) in human anterior segments implanted with a novel Schlemm's canal scaffold or two trabecular micro-bypasses.
  
  
  METHODS
  Human anterior segments were isolated from 12 pairs of eyes from donors with no history of ocular disease and then perfused at 50, 40, 30, 20, and 10 mm Hg pressures for 10 minutes each. Baseline C was calculated from perfusion pressures and flow rates. The scaffold was implanted into Schlemm's canal of one anterior segment, and two micro-bypasses were implanted three clock-hours apart in the contralateral anterior segment. Outflow facility and resistance were compared at various standardized perfusion pressures and between each device.
  
  
  RESULTS
  Compared to baseline, C increased by 0.16 ± 0.12 μL/min/mm Hg (74%) with the scaffold, and 0.08 ± 0.12 μL/min/mm Hg (34%) with two micro-bypasses. The scaffold increased C at perfusion pressures of 50, 40, 30, and 20 mm Hg (P < 0.005). Two micro-bypasses increased C at a perfusion pressure of 40 mm Hg (P < 0.05).
  
  
  CONCLUSIONS
  Both implants effectively increased C in human eyes ex vivo. The scaffold increased C by a greater percentage (73% vs. 34%) and at a greater range of perfusion pressures (20 to 50 mm Hg vs. 40 mm Hg) than the two micro-bypasses, suggesting that the 8-mm dilation of Schlemm's canal by the scaffold may have additional benefits in lowering the outflow resistance. The Hydrus Microstent scaffold may be an effective therapy for increasing outflow facility and thus reducing the IOP in patients with glaucoma.
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska.
authors.forename: Cassandra L
authors.initials: CL
authors.lastname: Hays
authors.forename: Vikas
authors.initials: V
authors.lastname: Gulati
authors.forename: Shan
authors.initials: S
authors.lastname: Fan
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Samuelson
authors.forename: Iqbal Ike K
authors.initials: II
authors.lastname: Ahmed
authors.forename: Carol B
authors.initials: CB
authors.lastname: Toris
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001082:Aqueous Humor / Q000502:physiology*; D005260:Female; D018463:Filtering Surgery / Q000379:methods*; D005901:Glaucoma / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D020327:Glaucoma Drainage Implants; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000379:methods*; D011474:Prosthesis Design; D014129:Trabecular Meshwork / Q000473:pathology* / Q000601:surgery
keywords: Schlemm's canal; drainage device; glaucoma anterior segment; outflow facility