title: Venous oxygen saturation is reduced and variable in central retinal vein occlusion.
abstract: OBJECTIVE
  To estimate the presence and variability of retinal hypoxia in patients with central retinal vein occlusion (CRVO).
  
  
  METHODS
  Hemoglobin oxygen saturation was measured in retinal vessels of both eyes in 14 patients with unilateral CRVO. The noninvasive spectrophotometric retinal oximeter is based on a fundus camera and simultaneously captures two images at 570 nm and 600 nm wavelengths. Five of the patients were followed with repeated retinal oximetry images over time.
  
  
  RESULTS
  The mean oxygen saturation in retinal venules was 31 % ±12 % in CRVO eyes and 52 % ±11 % in unaffected fellow eyes (mean ±SD, n = 14, p < 0.0001). The arteriovenous difference was 63 % ±11 % in eyes with CRVO and 43 % ±7 % in fellow eyes (p < 0.0001). The variability of retinal venous oxygen saturation was substantial within and between eyes affected by CRVO. Venular oxygen saturation improved with treatment and over time in all five patients that were followed.
  
  
  CONCLUSIONS
  CRVO eyes are hypoxic compared to fellow eyes and arteriovenous difference in hemoglobin oxygen saturation is increased. This is consistent with tissue hypoxia resulting from reduced blood flow. Further studies are needed to understand the correlation between hypoxia, severity of disease and prognosis.
authors.affiliation: University of Iceland, Reykjavik, Iceland. tse@hi.is.|Department of Opthalmolgy, Landspítali - The National University Hospital of Iceland, Eiriksgata 37, Reykjavik, Iceland. tse@hi.is.|Department of Anesthesiology, Landspítali - The National University Hospital of Iceland, Reykjavik, Iceland. tse@hi.is.
authors.forename: Thorunn Scheving
authors.initials: TS
authors.lastname: Eliasdottir
authors.affiliation: Department of Opthalmolgy, Landspítali - The National University Hospital of Iceland, Eiriksgata 37, Reykjavik, Iceland.
authors.forename: David
authors.initials: D
authors.lastname: Bragason
authors.affiliation: University of Iceland, Reykjavik, Iceland.|Department of Opthalmolgy, Landspítali - The National University Hospital of Iceland, Eiriksgata 37, Reykjavik, Iceland.
authors.forename: Sveinn Hakon
authors.initials: SH
authors.lastname: Hardarson
authors.affiliation: University of Iceland, Reykjavik, Iceland.
authors.forename: Gudrun
authors.initials: G
authors.lastname: Kristjansdottir
authors.affiliation: University of Iceland, Reykjavik, Iceland.|Department of Opthalmolgy, Landspítali - The National University Hospital of Iceland, Eiriksgata 37, Reykjavik, Iceland.
authors.forename: Einar
authors.initials: E
authors.lastname: Stefánsson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005451:Fluorescein Angiography; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010092:Oximetry; D010100:Oxygen / Q000097:blood*; D011446:Prospective Studies; D012039:Regional Blood Flow; D012169:Retinal Vein / Q000502:physiology*; D012170:Retinal Vein Occlusion / Q000503:physiopathology*; D014699:Venules / Q000502:physiology
chemical_list: D010100:Oxygen
keywords: Blood flow; Hypoxia; Oximetry; Oxygen; Retina; Vasculature