title: Intravascular oxygen saturation in retinal vessels in normal subjects and open-angle glaucoma subjects.
abstract: OBJECTIVE
  To measure the oxygen saturation (SO(2)) in retinal arterioles and venules in patients with glaucomatous optic neuropathy.
  
  
  METHODS
  We examined SO(2) in retinal arterioles and venules simultaneously by imaging spectrometry. Oxygen saturation was evaluated according to the difference of the extinction spectra of haemoglobin and oxyhaemoglobin. The arterio-venous difference (avD) was calculated by (SO(2art) - SO(2ven)). The optic nerve head topography was estimated by Heidelberg retinal tomography and the visual field using the Octopus G1. We examined one eye in each of 58 healthy persons (mean age 58.6 +/- 10.7 years; mean rim area 1.52 +/- 0.33 mm(2); mean defect 0.65 +/- 1.31 dB; mean intraocular pressure [IOP] 18.5 +/- 2.7 mmHg), 49 patients with normal-tension primary open-angle glaucoma (NTG) (mean age 63.0 +/- 8.5 years; mean rim area 0.89 +/- 0.34 mm(2); mean defect 5.4 +/- 4.1 dB; mean IOP 19.2 +/- 2.9 mmHg), and 45 patients with high-tension primary open-angle glaucoma (POAG) (mean age 62.6 +/- 10.3 years; mean rim area 0.97 +/- 0.47 mm(2); mean defect 7.1 +/- 6.4 dB; mean IOP 31.6 +/- 10.8 mmHg).
  
  
  RESULTS
  The intraclass correlation coefficients of the SO(2) measurement were 0.82 (arteriole) and 0.59 (venule). In normal eyes, the SO(2art), SO(2ven) and avD were 92.3 +/- 3.4%, 55.7 +/- 6.8% and 36.6 +/- 7.0%, respectively. Equivalent data were 89.7 +/- 5.4%, 56.0 +/- 8.3% and 33.7 +/- 10.6%, respectively, in NTG eyes and 91.4 +/- 4.0%, 58.3 +/- 10.5% and 33.1 +/- 11.5%, respectively, in POAG eyes. Over all examined eyes, the arteriolar SO(2) and the retinal arterio-venous difference correlated significantly with the rim area.
  
  
  CONCLUSIONS
  Eyes with NTG showed significantly decreased arteriolar SO(2). These changes were not seen in POAG patients.
authors.affiliation: Department of Ophthalmology, University of Erlangen-Nürnberg, Erlangen, Germany. Georg.Michelson@rzmail.uni-erlangen.de
authors.forename: Georg
authors.initials: G
authors.lastname: Michelson
authors.forename: Mateusz
authors.initials: M
authors.lastname: Scibor
mesh_terms: D005902:Glaucoma, Open-Angle / Q000097:blood*; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007429:Intraocular Pressure; D008875:Middle Aged; D010092:Oximetry / Q000379:methods; D010100:Oxygen / Q000097:blood*; D010108:Oxyhemoglobins / Q000032:analysis; D015203:Reproducibility of Results; D012161:Retinal Artery / Q000378:metabolism*; D012169:Retinal Vein / Q000378:metabolism*; D014786:Vision Disorders / Q000097:blood / Q000175:diagnosis; D014794:Visual Fields
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; D010100:Oxygen