title: Retinal Vessel Oxygen Saturation during 100% Oxygen Breathing in Healthy Individuals.
abstract: OBJECTIVE
  To detect how systemic hyperoxia affects oxygen saturation in retinal arterioles and venules in healthy individuals.
  
  
  METHODS
  Retinal vessel oxygen saturation was measured in 30 healthy individuals with a spectrophotometric retinal oximeter (Oxymap T1). Oximetry was performed during breathing of room air, 100% oxygen (10 minutes, 6L/min) and then again room air (10 minutes recovery).
  
  
  RESULTS
  Mean oxygen saturation rises modestly in retinal arterioles during 100% oxygen breathing (94.5%±3.8 vs. 92.0%±3.7% at baseline, p<0.0001) and dramatically in retinal venules (76.2%±8.0% vs. 51.3%±5.6%, p<0.0001). The arteriovenous difference decreased during 100% oxygen breathing (18.3%±9.0% vs. 40.7%±5.7%, p<0.0001). The mean diameter of arterioles decreased during 100% oxygen breathing compared to baseline (9.7±1.4 pixels vs. 10.3±1.3 pixels, p<0.0001) and the same applies to the mean venular diameter (11.4±1.2 pixels vs. 13.3±1.5 pixels, p<0.0001).
  
  
  CONCLUSIONS
  Breathing 100% oxygen increases oxygen saturation in retinal arterioles and more so in venules and constricts them compared to baseline levels. The dramatic increase in oxygen saturation in venules reflects oxygen flow from the choroid and the unusual vascular anatomy and oxygen physiology of the eye.
authors.affiliation: Department of Ophthalmology, University of Iceland, Reykjavik, Iceland; Department of Ophthalmology, Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland.
authors.forename: Olof Birna
authors.initials: OB
authors.lastname: Olafsdottir
authors.affiliation: Department of Ophthalmology, University of Iceland, Reykjavik, Iceland; Department of Ophthalmology, Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland.
authors.forename: Thorunn Scheving
authors.initials: TS
authors.lastname: Eliasdottir
authors.affiliation: Department of Ophthalmology, University of Iceland, Reykjavik, Iceland; Department of Ophthalmology, Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland.
authors.forename: Jona Valgerdur
authors.initials: JV
authors.lastname: Kristjansdottir
authors.affiliation: Department of Ophthalmology, University of Iceland, Reykjavik, Iceland; Department of Ophthalmology, Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland.
authors.forename: Sveinn Hakon
authors.initials: SH
authors.lastname: Hardarson
authors.affiliation: Department of Ophthalmology, University of Iceland, Reykjavik, Iceland; Department of Ophthalmology, Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland.
authors.forename: Einar
authors.initials: E
authors.lastname: Stefánsson
mesh_terms: D000328:Adult; D001160:Arterioles / Q000187:drug effects / Q000502:physiology; D005260:Female; D005654:Fundus Oculi; D006262:Health; D006801:Humans; D008297:Male; D010100:Oxygen / Q000494:pharmacology*; D012119:Respiration / Q000187:drug effects*; D012171:Retinal Vessels / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors; D014699:Venules / Q000187:drug effects / Q000528:radiation effects
chemical_list: D010100:Oxygen