title: [Optical Doppler velocimetry of red blood cells at different depths in retinal vessels by varying the coherence length of the source: feasibility study].
abstract: OBJECTIVE
  To report on a novel approach to measure the velocity of red blood cells (RBCs) at different retinal vessel depths.
  
  
  METHODS
  The technique is an extension of conventional laser Doppler velocimetry using light sources of various coherence lengths (CL). Light scattered by the moving RBCs interferes with that reflected from the anterior vessel wall only if the optical path difference is shorter than CL. Therefore, using low coherence light sources, localized measurements of RBCs velocity can be performed.
  
  
  RESULTS
  Measurements of RBCs velocity at different depths in a main retinal vein (diameter: 152 microns) of a volunteer has been performed using 4 different light sources with CLs of 14 microns, 21 microns, 32 microns and > m. Measured values are in good agreement with theoretically predicted values.
  
  
  CONCLUSIONS
  This new approach permits to measure RBCs velocity at different depths of retinal vessels in the human retina.
authors.affiliation: Institut de Recherche en Ophtalmologie (IRO), Sion, Suisse.
authors.forename: E
authors.initials: E
authors.lastname: Logean
authors.forename: L F
authors.initials: LF
authors.lastname: Schmetterer
authors.forename: M H
authors.initials: MH
authors.lastname: Geiser
authors.forename: C E
authors.initials: CE
authors.lastname: Riva
mesh_terms: D001783:Blood Flow Velocity; D002829:Choroid / Q000098:blood supply; D004909:Erythrocyte Indices; D004912:Erythrocytes / Q000502:physiology*; D005240:Feasibility Studies; D006801:Humans; D017078:Laser-Doppler Flowmetry / Q000379:methods*; D012171:Retinal Vessels / Q000502:physiology*
vernacular_title: Vélocimétrie par effet Doppler optique des globules rouges à différentes profondeurs dans les vaisseaux rétiniens en variant la longueur de cohérence temporelle de la source: etude de faisabilité.