title: Retinal oxygen saturation: novel analysis method for the oxymap.
abstract: OBJECTIVE
  To use a novel image analysis approach to consider how oxygen saturation changes as a function of vessel width and distance from the nerve and between superior and inferior retinal hemifields.
  
  
  METHODS
  Ten images were acquired from one eye of 17 participants (mean [standard deviation] age, 28 [4] years; range, 22-38 years) using the Oxymap T1 retinal oximeter. Every pixel identified by the detection algorithm was extracted, and frequency histograms of retinal vessel oxygen saturation were plotted for each vessel diameter (70-170 μm). Histograms were fitted with two Gaussian models to identify peak arteriole and venule oxygen saturation. Mean (±standard error of the mean) arteriole and venule oxygen saturation at each vessel width were calculated. Data were also analyzed in (1) annuli of 100 μm centered on the optic nerve or (2) upper and lower hemifields demarcated by the center of the optic nerve.
  
  
  RESULTS
  Venous oxygen saturation was higher in smaller vessels than in larger vessels. Arterial oxygen saturation remained relatively constant with vessel width. Oxygen saturation was lower in veins nearer the optic nerve. The upper retinal hemisphere showed higher venous oxygen saturation compared with the lower hemifield.
  
  
  CONCLUSIONS
  The current objective analysis approach provides a more complete picture of retinal oxygen saturation at the posterior pole as a function of vessel width and retinal location.
authors.affiliation: *BOptom †BSc (Hons) ‡PhD Department of Optometry and Vision Sciences (JPP, RAO, SLH, AJA, BVB), The University of Melbourne; and Australian College of Optometry (SLH), Melbourne, Victoria, Australia; and Department of Optometry (SLH), City University, London, United Kingdom.
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Paul
authors.forename: Rachael A
authors.initials: RA
authors.lastname: O'Connell
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Hosking
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Anderson
authors.forename: Bang V
authors.initials: BV
authors.lastname: Bui
mesh_terms: D000328:Adult; D000465:Algorithms; D001794:Blood Pressure / Q000502:physiology; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008962:Models, Theoretical; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000502:physiology*; D012171:Retinal Vessels / Q000502:physiology*; D055815:Young Adult
chemical_list: D010100:Oxygen