title: Retinal oximetry with a scanning laser ophthalmoscope.
abstract: OBJECTIVE
  The purpose of the study was to assess if a scanning laser ophthalmoscope (SLO), Optomap 200Tx, could be used for measurements of hemoglobin oxygen saturation in retinal blood vessels.
  
  
  METHODS
  Optomap 200Tx uses two lasers for image acquisition, 532 and 633 nm. Retinal images of healthy individuals and patients with retinal vein occlusion were analyzed with modified Oxymap Analyzer software, which tracks retinal vessels and calculates relative hemoglobin oxygen saturation.
  
  
  RESULTS
  Oxygen saturation in healthy individuals was measured as 92% ± 13% for arterioles and 57% ± 12% for venules (mean ± SD, n = 11, P = 0.0001). Standard deviation for repeated measurements of the same eye was 3.5% for arterioles and 4.4% for venules. In patients with confirmed venular hypoxia, central retinal vein occlusion (CRVO) or hemivein occlusion, the average venular oxygen saturation was measured as 23% ± 3% in the affected eyes and 59% ± 3% in the fellow eyes (n = 4, P = 0.0009).
  
  
  CONCLUSIONS
  Technically, it is possible to derive information on retinal oxygen saturation from an SLO with a 2-wavelength oximetry algorithm. The system produced both sensitive and repeatable results. The remaining challenges include decreasing variability between vessels of the same eye and variability between individuals. Given the advantages that SLO imaging has over conventional fundus camera optics in retinal oximetry, further development of SLO oximetry may provide the optimal approach to retinal oximetry.
authors.affiliation: Department of Ophthalmology, Landspitali University Hospital, Reykjavik, Iceland University of Iceland, Reykjavik, Iceland.
authors.forename: Jona Valgerdur
authors.initials: JV
authors.lastname: Kristjansdottir
authors.affiliation: Department of Ophthalmology, Landspitali University Hospital, Reykjavik, Iceland University of Iceland, Reykjavik, Iceland.
authors.forename: Sveinn Hakon
authors.initials: SH
authors.lastname: Hardarson
authors.affiliation: Oxymap ehf., Reykjavik, Iceland.
authors.forename: Gisli Hreinn
authors.initials: GH
authors.lastname: Halldorsson
authors.affiliation: Oxymap ehf., Reykjavik, Iceland.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Karlsson
authors.affiliation: Department of Ophthalmology, Landspitali University Hospital, Reykjavik, Iceland University of Iceland, Reykjavik, Iceland.
authors.forename: Thorunn S
authors.initials: TS
authors.lastname: Eliasdottir
authors.affiliation: Department of Ophthalmology, Landspitali University Hospital, Reykjavik, Iceland University of Iceland, Reykjavik, Iceland.
authors.forename: Einar
authors.initials: E
authors.lastname: Stefánsson
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal / Q000295:instrumentation*; D008875:Middle Aged; D019721:Ophthalmoscopes; D009887:Ophthalmoscopy / Q000379:methods*; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000097:blood*; D015203:Reproducibility of Results; D012170:Retinal Vein Occlusion / Q000503:physiopathology*; D012171:Retinal Vessels / Q000502:physiology*; D012680:Sensitivity and Specificity
chemical_list: D010100:Oxygen
keywords: hemoglobin; hyperoxia; hypoxia; oxygen; retina