title: Reproducibility of retinal oximetry measurements in healthy and diseased retinas.
abstract: OBJECTIVE
  Retinal oximetry (RO) has been established as a non-invasive method to analyse oxygen saturation in retinal vessels. The aim of our study was to determine the reproducibility of RO images in healthy and in diseased retinas.
  
  
  METHODS
  A total of 61 right eyes (244 RO images) in 61 subjects (35♀, 26♂) were examined: 22 controls, 18 patients with glaucoma and 21 patients with inherited retinal diseases (IRDs). Four test-retest RO images were obtained in each subject. Oxygen saturation was measured with the oxygen saturation measurement tool of the Retinal Vessel Analyser (RVA; IMEDOS Systems UG, Jena, Germany). The test-retest standard deviation within the subject's (±SDw ) measurements (the mean vessel oxygen saturation in retinal venules and arterioles), its coefficient of variation (CoV) and the intraclass correlation coefficients (ICC) were analysed.
  
  
  RESULTS
  The average test-retest SDw in venules was ±2.52% (CoV = 4.35%) and in arterioles was ±1.67% (CoV = 1.76%). Among controls, glaucoma eyes and eyes with IRDs, the test-retest SDw in venules were ±2.33% (CoV = 4.48%), ±2.85% (CoV = 4.71%) and ±2.43% (CoV = 3.90%) (SDw p = 0.366 (CoV p = 0.452); one-way anova). The test-retest SDw in arterioles were ±1.65% (CoV = 1.80%), ±1.83% (CoV = 1.92%) and ±1.54% (CoV = 1.56%), respectively [SDw p = 0.762 (CoV p = 0.686)]. The ICCs in venules were 0.76 in controls, 0.69 in patients with glaucoma and 0.82 in patients with IRD. The ICCs in arterioles were, respectively, 0.92, 0.70 and 0.93.
  
  
  CONCLUSIONS
  The reproducibility of RO in healthy, as well as in diseased retinas, is excellent. In the glaucoma group, the lower standard deviation between subjects (SDb ) for arterioles contributes to the lower ICCs. Nevertheless, the measurements of oxygen saturation in arterioles seem more reliable when compared to venules.
authors.affiliation: Department of Ophthalmology, University of Basel, Basel, Switzerland.
authors.forename: Cengiz
authors.initials: C
authors.lastname: Türksever
authors.affiliation: Department of Ophthalmology, University of Basel, Basel, Switzerland.
authors.forename: Selim
authors.initials: S
authors.lastname: Orgül
authors.affiliation: Department of Ophthalmology, University of Basel, Basel, Switzerland.
authors.forename: Margarita G
authors.identifier: http://orcid.org/0000-0001-8326-1449
authors.initials: MG
authors.lastname: Todorova
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001160:Arterioles / Q000502:physiology; D005260:Female; D005901:Glaucoma / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010092:Oximetry / Q000592:standards*; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption; D015203:Reproducibility of Results; D012162:Retinal Degeneration / Q000503:physiopathology*; D012171:Retinal Vessels / Q000502:physiology*; D014699:Venules / Q000502:physiology; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: controls; glaucoma; inherited diseases of the retina; oxygen saturation; reproducibility; retinal vessel oximetry