title: Impact of Corneal Endothelial Dysfunctions on Intraocular Oxygen Levels in Human Eyes.
abstract: OBJECTIVE
  We studied the implications of corneal endothelial dysfunctions on oxidative stress in the anterior segment via in vivo measurements of oxygen partial pressure (pO2) in the anterior chamber (AC) of human eyes.
  
  
  METHODS
  We recruited 51 patients undergoing cataract surgery and/or endothelial keratoplasty (EK). Endothelial cell density (ECD; n = 33) and central corneal thickness (CCT; n = 41) were measured on patients with relatively clear corneas. Before surgery, an oxygen sensor was introduced into the AC via a peripheral corneal paracentesis. In all patients, seven measurements of pO2 were obtained by positioning the flexible tip near the endothelium at the central cornea, at four cardinal subendothelial locations near the midperipheral cornea, and in the mid-AC and AC angle. In patients with pseudophakia or eyes undergoing cataract surgery, pO2 also was measured near the lens surface and in the posterior chamber.
  
  
  RESULTS
  Consistent with our previous reports, a steep oxygen gradient was noted in the anterior segment of normal controls (n = 24). In patients with endothelial dysfunctions (n = 27), there was a significant increase of pO2 at all five subendothelial locations without a significant increase of pO2 in the AC angle. By regression analyses, subendothelial pO2 correlated inversely with ECD and positively with CCT in patients with endothelial dysfunctions.
  
  
  CONCLUSIONS
  This study demonstrates an even steeper intraocular oxygen gradient in eyes with corneal endothelial dysfunctions. It suggests that the reduced oxygen consumption in corneal endothelial cells may increase oxidative stress in the AC and the existence of an alternative aqueous inflow pathway that maintains a relatively low and constant pO2 at the AC angle.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, United States.
authors.forename: Andrew J W
authors.initials: AJ
authors.lastname: Huang
authors.affiliation: Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, United States.
authors.forename: Ying-Bo
authors.initials: YB
authors.lastname: Shui
authors.affiliation: Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, United States 2Shanxi Eye Hospital, Taiyuan, Shanxi, China.
authors.forename: Yu-Ping
authors.initials: YP
authors.lastname: Han
authors.affiliation: Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, United States.
authors.forename: Fang
authors.initials: F
authors.lastname: Bai
authors.affiliation: Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, United States.
authors.forename: Carla J
authors.initials: CJ
authors.lastname: Siegfried
authors.affiliation: Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, United States 3Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri, United States.
authors.forename: David C
authors.initials: DC
authors.lastname: Beebe
mesh_terms: D000368:Aged; D001082:Aqueous Humor / Q000378:metabolism*; D002386:Cataract / Q000378:metabolism* / Q000473:pathology; D002452:Cell Count; D003430:Cross-Sectional Studies; D004728:Endothelium, Corneal / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*
chemical_list: D010100:Oxygen