title: INTRAOCULAR PRESSURE CHANGES DURING VITRECTOMY USING CONSTELLATION VISION SYSTEM'S INTRAOCULAR PRESSURE CONTROL FEATURE.
abstract: OBJECTIVE
  To evaluate intraocular pressure (IOP) changes during experimental vitrectomy and the efficacy of Constellation Vision System's IOP control (IOPc) feature in reestablishing baseline pressure.
  
  
  METHODS
  Using a pressure transducer in freshly enucleated porcine eyes, a broad range of parameters (baseline pressures, aspiration levels, and cut rates) were tested with 23- and 25-gauge probes and IOPc turned ON versus OFF.
  
  
  RESULTS
  IOPc turned ON was significantly more effective than IOPc turned OFF in controlling IOP drop and stabilizing pressure during vitrectomy using a wide range of baseline pressures (20-70 mmHg). The 23-gauge system consistently presented a reduced drop from baseline compared with the 25-gauge system. The overall average drop for the 23- and 25-gauge systems was 12.79 mmHg and 21.17 mmHg, respectively. Both gauge sizes reestablished baseline pressure approximately 1.6 seconds after the initial pressure drop generated at the beginning of aspiration. A peak of IOP (overshooting) was observed when the pressure was returning to baseline using both 23- and 25-gauge systems.
  
  
  CONCLUSIONS
  Using IOPc feature turned ON, 23- and 25-gauge probes were effective in reestablishing and sustaining baseline infusion pressures, although 23-gauge probes showed less IOP fluctuation than did 25-gauge probes.
authors.affiliation: *Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, California; †Department of Ophthalmology and Visual Sciences, Federal University of São Paulo, São Paulo, Brazil; ‡Department of Ophthalmology, University of Heidelberg, Heidelberg, Germany; and §School of Medicine, Catholic University of Brasília, Brasília, Brazil.
authors.forename: Paulo
authors.initials: P
authors.lastname: Falabella
authors.forename: Francisco R
authors.initials: FR
authors.lastname: Stefanini
authors.forename: Jaw-Chyng L
authors.initials: JC
authors.lastname: Lue
authors.forename: Marcel
authors.initials: M
authors.lastname: Pfister
authors.forename: Jahlyn
authors.initials: J
authors.lastname: Reyes-Mckinley
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Koss
authors.forename: Anderson
authors.initials: A
authors.lastname: Teixeira
authors.forename: Paulo
authors.initials: P
authors.lastname: Schor
authors.forename: Mark S
authors.initials: MS
authors.lastname: Humayun
mesh_terms: D000818:Animals; D007429:Intraocular Pressure / Q000502:physiology*; D012599:Sclerostomy; D013552:Swine; D014065:Tonometry, Ocular; D014160:Transducers, Pressure; D014821:Vitrectomy