title: Central corneal thickness correlates with oxygen levels in the human anterior chamber angle.
abstract: OBJECTIVE
  To measure oxygen (pO2) in eyes of patients undergoing intraocular surgery and identify correlations with central corneal thickness (CCT).
  
  
  METHODS
  Prospective, cross-sectional study.
  
  
  METHODS
  setting: Institutional. patient population: 124 patients undergoing cataract and/or glaucoma surgery. observation procedure: Prior to surgery, an oxygen sensor was introduced into the anterior chamber (AC) via peripheral corneal paracentesis. The tip of the flexible fiberoptic probe was positioned for 3 measurements in all patients: (1) near central corneal endothelium; (2) in mid-AC; and (3) in AC angle. In patients undergoing cataract extraction, additional measurements were taken (4) at the anterior lens surface and (5) in the posterior chamber. main outcome measures: pO2 measurements at 5 locations within the eye were compared to central corneal thickness measurements by multivariate regression analyses.
  
  
  RESULTS
  There was a statistically significant inverse correlation between CCT and pO2 in the anterior chamber angle (P = .048). pO2 was not significantly related to CCT at any other location, including beneath the central cornea. Regression analysis relating CCT to age, race, and oxygen levels in all 5 locations in the anterior segment revealed an association of a thinner cornea with increasing age (P = .007).
  
  
  CONCLUSIONS
  Physiologic correlations with central corneal thickness may provide clues to understanding why a thinner cornea increases the risk of open glaucoma. Associations between glaucoma risk, CCT, and pO2 in the AC angle suggest that exposure of the outflow system to increased oxygen or oxygen metabolites may increase oxidative damage to the trabecular meshwork cells, resulting in elevation of intraocular pressure.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St Louis, Missouri. Electronic address: siegfried@vision.wustl.edu.
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.
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.
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; Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, Missouri.
authors.forename: David C
authors.initials: DC
authors.lastname: Beebe
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000867:Anterior Chamber / Q000378:metabolism*; D057919:Biological Oxygen Demand Analysis; D015374:Biosensing Techniques; D003315:Cornea / Q000033:anatomy & histology*; D003430:Cross-Sectional Studies; D005260:Female; D005902:Glaucoma, Open-Angle / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D010100:Oxygen / Q000378:metabolism*; D010313:Partial Pressure; D018918:Phacoemulsification; D011446:Prospective Studies
chemical_list: D010100:Oxygen