title: Oxygen distribution in the human eye: relevance to the etiology of open-angle glaucoma after vitrectomy.
abstract: OBJECTIVE
  Vitrectomy, when followed by cataract surgery, increases the risk of open-angle glaucoma. This study was conducted in patients to determine whether these procedures are associated with increased exposure of the trabecular meshwork to oxygen.
  
  
  METHODS
  Oxygen distribution was recorded with a fiberoptic probe in patients undergoing surgery for cataract, glaucoma, or retinal disease. pO(2) was measured beneath the central cornea, in the mid-anterior chamber, and in the anterior chamber angle. In patients who were pseudophakic or were scheduled for cataract extraction, pO(2) was also measured in the posterior chamber and near the lens.
  
  
  RESULTS
  Eyes with no previous cataract or vitrectomy surgery had steep oxygen gradients in the aqueous humor between the cornea and lens. pO(2) was low in the posterior chamber and near the lens. Previous vitrectomy was associated with significantly increased pO(2) in the posterior chamber. Eyes with previous cataract surgery had significantly elevated pO(2) only in the posterior chamber and in front of the intraocular lens (IOL). Eyes that had both vitrectomy and previous cataract surgery had increased pO(2) in the posterior chamber, anterior to the IOL, and in the anterior chamber angle. pO(2) in the posterior chamber and the anterior chamber angle correlated strongly.
  
  
  CONCLUSIONS
  Oxygen metabolism by the lens and cornea establishes oxygen gradients in the anterior segment. Vitrectomy and cataract surgery increase pO(2) in the anterior chamber angle, potentially damaging trabecular meshwork cells. We propose that oxygen levels in the anterior chamber angle are strongly influenced by oxygen derived from the ciliary body circulation.
authors: Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri 63110, USA. siegfried@vision.wustl.edu
authors: Carla J
authors: CJ
authors: Siegfried
authors: Ying-Bo
authors: YB
authors: Shui
authors: Nancy M
authors: NM
authors: Holekamp
authors: Fang
authors: F
authors: Bai
authors: David C
authors: DC
authors: Beebe
mesh_terms: D000368:Aged; D002387:Cataract Extraction; D003430:Cross-Sectional Studies; D005260:Female; D005902:Glaucoma, Open-Angle / Q000209:etiology* / Q000378:metabolism*; D006801:Humans; D017736:Ion-Selective Electrodes; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress; D010092:Oximetry; D010100:Oxygen / Q000378:metabolism*; D010313:Partial Pressure; D019591:Pseudophakia / Q000209:etiology / Q000378:metabolism; D012164:Retinal Diseases / Q000601:surgery; D018570:Risk Assessment; D014129:Trabecular Meshwork / Q000378:metabolism*; D014130:Trabeculectomy; D014821:Vitrectomy
chemical_list: D010100:Oxygen