title: Ocular Blood Flow Measurements in Healthy White Subjects Using Laser Speckle Flowgraphy.
abstract: OBJECTIVE
  To assess the feasibility and reliability of Laser Speckle Flowgraphy (LSFG) to measure ocular perfusion in a sample of healthy white subjects and to elucidate the age-dependence of the parameters obtained.
  
  
  METHODS
  This cross-sectional study included 80 eyes of 80 healthy, non-smoking white subjects of Western European descent between 19 and 79 years of age. A commercial LSFG instrument was applied to measure ocular blood flow at the optic nerve head (ONH) three successive times before and after pharmacological pupil dilation. The mean blur rate (MBR), a measure of relative blood flow velocity, was obtained for different regions of the ONH. Eight parameters of ocular perfusion derived from the pulse-waveform analysis of MBR including blowout time (BOT) and falling rate (FR) were also recorded.
  
  
  RESULTS
  Artifact-free LSFG images meeting the quality criteria for automated image analysis were obtainable in 93.8% without pupil dilation and in 98.8% with pharmacological pupil dilation. Measurements of MBR showed excellent repeatability with intraclass correlation coefficients ≥ 0.937 and were barely affected by pupil dilation. The majority of pulse-waveform derived variables exhibited equally high repeatability. MBR-related blood flow indices exhibited significant age dependence (p<0.001). FR (r = 0.747, p<0.001) and BOT (r = -0.714, p<0.001) most strongly correlated with age.
  
  
  CONCLUSIONS
  LSFG represents a reliable method for the quantitative assessment of ocular blood flow in white subjects. Our data affirms that the LSFG-derived variables FR and BOT may be useful biomarkers for age-related changes in ocular perfusion.
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.|Department of Ophthalmology, Kepler University Hospital, Linz, Austria.|University Eye Hospital, Ludwig Maximilians University, Munich, Germany.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Luft
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.|Department of Ophthalmology, Medical University of Warsaw, Warsaw, Poland.
authors.forename: Piotr A
authors.initials: PA
authors.lastname: Wozniak
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.|Institute of Applied Physics, Vienna University of Technology, Vienna, Austria.
authors.forename: Gerold C
authors.initials: GC
authors.lastname: Aschinger
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
authors.forename: Klemens
authors.initials: K
authors.lastname: Fondi
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Bata
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.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.|Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
authors.forename: Doreen
authors.initials: D
authors.lastname: Schmidl
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
authors.forename: Katarzyna J
authors.initials: KJ
authors.lastname: Witkowska
authors.affiliation: Department of Ophthalmology, Kepler University Hospital, Linz, Austria.
authors.forename: Matthias
authors.initials: M
authors.lastname: Bolz
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Garhöfer
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.|Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.|Singapore Eye Research Institute, Singapore.|Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore.
authors.forename: Leopold
authors.initials: L
authors.lastname: Schmetterer
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D016477:Artifacts; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D003430:Cross-Sectional Studies; D005260:Female; D064368:Healthy Volunteers; D006439:Hemodynamics; D006801:Humans; D007091:Image Processing, Computer-Assisted; D017078:Laser-Doppler Flowmetry; D007834:Lasers; D008297:Male; D008833:Microcirculation / Q000502:physiology; D008875:Middle Aged; D009898:Optic Disk / Q000098:blood supply*; D010858:Pigmentation; D011680:Pupil / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D015203:Reproducibility of Results; D012737:Sex Factors; D013997:Time Factors; D044465:White People; D055815:Young Adult