title: Response of retinal blood flow to systemic hyperoxia as measured with dual-beam bidirectional Doppler Fourier-domain optical coherence tomography.
abstract: OBJECTIVE
  There is a long-standing interest in the study of retinal blood flow in humans. In the recent years techniques have been established to measure retinal perfusion based on optical coherence tomography (OCT). In the present study we used a technique called dual-beam bidirectional Doppler Fourier-domain optical coherence tomography (FD-OCT) to characterize the effects of 100% oxygen breathing on retinal blood flow. These data were compared to data obtained with a laser Doppler velocimeter (LDV).
  
  
  METHODS
  10 healthy subjects were studied on 2 study days. On one study day the effect of 100% oxygen breathing on retinal blood velocities was studied using dual-beam bidirectional Doppler FD-OCT. On the second study day the effect of 100% oxygen breathing on retinal blood velocities was assessed by laser Doppler velocimetry (LDV). Retinal vessel diameters were measured on both study days using a commercially available Dynamic Vessel Analyzer. Retinal blood flow was calculated based on retinal vessel diameters and red blood cell velocity.
  
  
  RESULTS
  As expected, breathing of pure oxygen induced a pronounced reduction in retinal vessel diameters, retinal blood velocities and retinal blood flow on both study days (p<0.001). Blood velocity data correlated well between the two methods applied under both baseline as well as under hyperoxic conditions (r = 0.98 and r = 0.75, respectively). Data as obtained with OCT were, however, slightly higher.
  
  
  CONCLUSIONS
  A good correlation was found between red blood cell velocity as measured with dual-beam bidirectional Doppler FD-OCT and red blood cell velocity assessed by the laser Doppler method. Dual-beam bidirectional Doppler FD-OCT is a promising approach for studying retinal blood velocities in vivo.
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
authors.forename: René M
authors.initials: RM
authors.lastname: Werkmeister
authors.forename: Stefan
authors.initials: S
authors.lastname: Palkovits
authors.forename: Reinhard
authors.initials: R
authors.lastname: Told
authors.forename: Martin
authors.initials: M
authors.lastname: Gröschl
authors.forename: Rainer A
authors.initials: RA
authors.lastname: Leitgeb
authors.forename: Gerhard
authors.initials: G
authors.lastname: Garhöfer
authors.forename: Leopold
authors.initials: L
authors.lastname: Schmetterer
mesh_terms: D000328:Adult; D000465:Algorithms; D001783:Blood Flow Velocity; D005583:Fourier Analysis; D006801:Humans; D018496:Hyperoxia / Q000503:physiopathology*; D010100:Oxygen / Q000494:pharmacology; D012171:Retinal Vessels / Q000378:metabolism / Q000502:physiology*; D041623:Tomography, Optical Coherence; D014661:Vasoconstriction / Q000187:drug effects; D055815:Young Adult
chemical_list: D010100:Oxygen