title: Assessment of retinal and choroidal blood flow changes using laser Doppler flowmetry in rats.
abstract: OBJECTIVE
  A new noninvasive laser Doppler flowmetry (LDF) probe (one emitting fiber surrounded by a ring of eight collecting fibers, 1-mm interaxis distance) was tested for its sensitivity to assess the retinal/choroidal blood flow variations in response to hypercapnia, hyperoxia, diverse vasoactive agents and following retinal arteries photocoagulation in the rat.
  
  
  METHODS
  After pupil dilation, a LDF probe was placed in contact to the cornea of anesthetized rats in the optic axis. Hypercapnia and hyperoxia were induced by inhalation of CO(2) (8% in medical air) and O(2) (100%) while pharmacological agents were injected intravitreously. The relative contribution of the choroidal circulation to the LDF signal was estimated after retinal artery occlusion by photocoagulation.
  
  
  RESULTS
  Blood flow was significantly increased by hypercapnia (18%), adenosine (14%) and sodium nitroprusside (16%) as compared to baseline values while it was decreased by hyperoxia (-8%) and endothelin-1 (-11%). Photocoagulation of retinal arteries significantly decreased blood flow level (-45%).
  
  
  CONCLUSIONS
  Although choroidal circulation most likely contributes to the LDF signal in this setting, the results demonstrate that LDF represents a suitable in vivo noninvasive technique to monitor online relative reactivity of retinal perfusion to metabolic or pharmacological challenge. This technique could be used for repeatedly assessing blood flow reactivity in rodent models of ocular diseases.
authors.affiliation: School of Optometry, Université de Montréal, Montréal, Québec, Canada.
authors.forename: Simon
authors.initials: S
authors.lastname: Hétu
authors.forename: Mylène
authors.initials: M
authors.lastname: Pouliot
authors.forename: Ghassan
authors.initials: G
authors.lastname: Cordahi
authors.forename: Réjean
authors.initials: R
authors.lastname: Couture
authors.forename: Elvire
authors.initials: E
authors.lastname: Vaucher
mesh_terms: D000818:Animals; D002829:Choroid / Q000098:blood supply*; D004195:Disease Models, Animal; D017075:Laser Coagulation; D017078:Laser-Doppler Flowmetry / Q000379:methods*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D051381:Rats; D017208:Rats, Wistar; D012039:Regional Blood Flow / Q000502:physiology*; D015203:Reproducibility of Results; D012161:Retinal Artery / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D015356:Retinal Artery Occlusion / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery