title: Reproducibility of retinal vessel oxygen saturation measurements in healthy young subjects.
abstract: OBJECTIVE
  An adequate oxygenation and perfusion is essential for the function of the inner retina. Recently, several techniques for the measurement of retinal oxygen saturation became available. We set out to evaluate reproducibility of the measurements using a modified Retinal Vessel Analyzer.
  
  
  METHODS
  A total of 20 healthy female and male subjects aged between 18 and 35 years (22.9 ± 3.9; mean ± SD) were included. The measurement of retinal oxygen saturation with the retinal oximeter employed in this study is based on optical reflectometry using the different absorption characteristics of oxygenated and deoxygenated haemoglobin. The intraclass correlation coefficients and the coefficients of variation (CV) for test-retest, short-term as well as day-to-day measurements were calculated.
  
  
  RESULTS
  The intraclass correlation coefficients were between 0.91 and 0.94 for retinal branch arteries and between 0.84 and 0.88 for retinal branch veins. In retinal arteries, we calculated a test-retest CV of 3.24 ± 3.18% for oxygen saturation measurements. In retinal veins, data were slightly less reproducible with a CV of 4.92 ± 3.57%. Short-term reproducibility of both measurement cycles on each study day was in the same range (CV in retinal arteries: 2.91 ± 2.42% and CV in retinal veins: 4.76 ± 3.14%). The day-to-day coefficient of variation was slightly higher (CV in retinal arteries: 3.97 ± 2.87% and CV in retinal veins: 6.18 ± 3.36%).
  
  
  CONCLUSIONS
  The reproducibility of haemoglobin oxygen saturation measurements using the retinal oximeter is acceptable. Further studies on the validity of the obtained results are, however, required.
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Lasta
authors.forename: Stefan
authors.initials: S
authors.lastname: Palkovits
authors.forename: Agnes
authors.initials: A
authors.lastname: Boltz
authors.forename: Doreen
authors.initials: D
authors.lastname: Schmidl
authors.forename: Semira
authors.initials: S
authors.lastname: Kaya
authors.forename: Alina Popa
authors.initials: AP
authors.lastname: Cherecheanu
authors.forename: Gerhard
authors.initials: G
authors.lastname: Garhöfer
authors.forename: Leopold
authors.initials: L
authors.lastname: Schmetterer
mesh_terms: D000293:Adolescent; D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D010092:Oximetry / Q000379:methods; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000502:physiology; D010991:Plethysmography; D015203:Reproducibility of Results; D012161:Retinal Artery / Q000502:physiology*; D012169:Retinal Vein / Q000502:physiology*; D055815:Young Adult
chemical_list: D006454:Hemoglobins; D010100:Oxygen