title: Noninvasive investigations of the normal ocular circulation in humans.
abstract: OBJECTIVE
  To compare the reproducibility of laser interferometric measurements of fundus pulsation, pneumatonometric measurement of pulse amplitude (PA) and pulsatile ocular blood flow (POBF), and Doppler ultrasonic measurements of blood flow velocity in the ophthalmic artery (OA) and the posterior ciliary arteries (PCAs) and to investigate the association of the results obtained with these methods and to characterize ocular hemodynamics during Valsalva maneuver and isometric handgrip.
  
  
  METHODS
  All studies were performed in healthy subjects. Fundus pulsation (n = 48), POBF (n = 24), and blood flow velocities (n = 24) were measured at baseline and during the Valsalva maneuver and isometric handgrip. Intraclass correlation coefficients were calculated for test/retest variability, for short-term variability, and for interobserver variability.
  
  
  RESULTS
  Intraclass correlation coefficients were between 0.95 and 0.98 for fundus pulsation measurements, between 0.54 and 0.76 for pneumatonometric measurements, between 0.44 and 0.88 for Doppler sonographic measurements in the OA and between 0.32 and 0.60 in the PCAs. There was a high degree of association between pneumatonometric parameters and fundus pulsation amplitude. Valsalva maneuver significantly reduced fundus pulsations, PA, and POBF, whereas isometric handgripping did not change these parameters.
  
  
  CONCLUSIONS
  The reproducibility of fundus pulsation measurements was excellent. Reproducibility of pneumatonometric parameters and ultrasonographic measurements in the OA was satisfactory. Reproducibility of ultrasonographic measurements in the PCAs was low. Data obtained during the autonomic stimuli experiments argue against the sole use of systems to measure pulsatile blood flow, if no additional data on flow pulsatility are available. At least in cases when changes in blood pressure are likely to occur the ratio of pulsatile to nonpulsatile blood flow might not be constant and POBF might not be an adequate measure of total ocular blood flow.
authors.affiliation: Department of Clinical Pharmacology, and Institute of Medical Physics, University of Vienna, Austria.
authors.forename: L
authors.initials: L
authors.lastname: Schmetterer
authors.forename: S
authors.initials: S
authors.lastname: Dallinger
authors.forename: O
authors.initials: O
authors.lastname: Findl
authors.forename: K
authors.initials: K
authors.lastname: Strenn
authors.forename: U
authors.initials: U
authors.lastname: Graselli
authors.forename: H G
authors.initials: HG
authors.lastname: Eichler
authors.forename: M
authors.initials: M
authors.lastname: Wolzt
mesh_terms: D000328:Adult; D001775:Blood Circulation; D001783:Blood Flow Velocity; D001784:Blood Gas Analysis; D019842:Ciliary Arteries / Q000502:physiology*; D005123:Eye / Q000098:blood supply*; D005260:Female; D005654:Fundus Oculi; D006801:Humans; D007368:Interferometry; D007429:Intraocular Pressure / Q000502:physiology; D007537:Isometric Contraction / Q000502:physiology; D017078:Laser-Doppler Flowmetry; D007834:Lasers; D008297:Male; D009880:Ophthalmic Artery / Q000502:physiology*; D015203:Reproducibility of Results; D014065:Tonometry, Ocular; D014636:Valsalva Maneuver / Q000502:physiology