title: Retinal oxygen metabolism in healthy subjects and glaucoma patients.
abstract: BACKGROUND
  To test whether retinal oxygen metabolism is different in glaucoma patients compared with healthy subjects.
  
  
  METHODS
  This was a two-centre study where retinal vessel oxygen saturation was measured in glaucoma patients and healthy individuals with a non-invasive spectrophotometric retinal oximeter. Visual fields were obtained in the glaucoma patients.
  
  
  RESULTS
  No statistical difference was found in retinal oxygen saturation in arterioles (p=0.16), venules (p=0.16) and arteriovenous difference (p=0.24) when all glaucoma patients (n=74) were compared with healthy individuals (n=89). When patients with advanced glaucoma (visual field mean defect (MD ≥ 10 dB, n=21)) were compared with healthy individuals, the oxygen saturation in venules was higher in glaucoma patients (58.2% ± 5.4% vs 53.8% ± 6.4%; p=0.0054, mean ± SD) and the arteriovenous difference was lower in glaucoma patients (36.4% ± 4.7% vs 39.5% ± 5.7%; p=0.021). In glaucoma patients with mild glaucoma (visual field MD ≤ 5 dB, n=33), no statistical differences were found in retinal oxygen saturation compared with healthy individuals.
  
  
  CONCLUSIONS
  Glaucoma patients with advanced glaucoma have higher oxygen saturation in venules and lower arteriovenous difference in oxygen saturation compared with healthy individuals. The decreased arteriovenous difference in severe glaucoma may be related to lower oxygen consumption secondary to neuropathy.
authors.affiliation: Department of Ophthalmology, University of Iceland, , Reykjavik, Iceland.
authors.forename: Olof Birna
authors.initials: OB
authors.lastname: Olafsdottir
authors.forename: Evelien
authors.initials: E
authors.lastname: Vandewalle
authors.forename: Luis
authors.initials: L
authors.lastname: Abegão Pinto
authors.forename: Asbjorg
authors.initials: A
authors.lastname: Geirsdottir
authors.forename: Eline
authors.initials: E
authors.lastname: De Clerck
authors.forename: Peter
authors.initials: P
authors.lastname: Stalmans
authors.forename: Maria Soffia
authors.initials: MS
authors.lastname: Gottfredsdottir
authors.forename: Jona Valgerdur
authors.initials: JV
authors.lastname: Kristjansdottir
authors.forename: Joachim
authors.initials: J
authors.lastname: Van Calster
authors.forename: Thierry
authors.initials: T
authors.lastname: Zeyen
authors.forename: Einar
authors.initials: E
authors.lastname: Stefánsson
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Stalmans
mesh_terms: D001794:Blood Pressure / Q000502:physiology; D003623:Dark Adaptation; D005260:Female; D005902:Glaucoma, Open-Angle / Q000503:physiopathology*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D057066:Low Tension Glaucoma / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010092:Oximetry; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000502:physiology; D011446:Prospective Studies; D012171:Retinal Vessels / Q000502:physiology*; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology
chemical_list: D010100:Oxygen
keywords: Glaucoma; Imaging; Physiology; Retina