title: Reproducibility of blood flow velocity measurements using colour decoded Doppler imaging.
abstract: BACKGROUND
  It is taken for granted that glaucomatous damage is caused by changed haemodynamics of the retrobulbar vessel system besides other factors such as, for example, an elevated intraocular pressure. This was proven by various studies in which glaucoma patients were shown to have a changed retrobulbar blood flow velocity. In this study, the reliability of measurements of retrobulbar vessel perfusion by colour decoded Doppler imaging (CDI) was evaluated.
  
  
  METHODS
  A total of 18 healthy volunteers and 15 patients with various glaucoma types were enrolled in this study. Using a CDI system, type Siemens Sonoline Elegra with a combined applicator (7.5L40), retrobulbar vessel perfusions of the ophthalmic artery, the short posterior ciliary arteries, and the long posterior ciliary arteries of each patient were measured six times. In each measurement, pulse amplitude, end-diastolic velocity, maximum systolic velocity, pulsatility index, and resistivity index of the vessels were determined. The reproducibility of measurements was evaluated by the calculation of the intraclass correlation coefficient (ICC) for each parameter.
  
  
  RESULTS
  The ICCs for the ophthalmic artery varied from 0.89 to 0.98, for the short posterior ciliary artery from 0.75 to 0.91, and for the long posterior ciliary artery from 0.77 to 0.99 in both the groups.
  
  
  CONCLUSIONS
  The ICCs of the repeated measurements reflect a good reproducibility for both the groups with assumed different retrobulbar perfusion. These findings are prerequisites for the use of CDI in clinical practice and research.
authors.affiliation: Universitätsklinikum Hamburg-Eppendorf, Klinik und Poliklinik für Augenheilkunde, Hamburg, Germany. e.matthiessen@uke.uni-hamburg.de
authors.forename: E T
authors.initials: ET
authors.lastname: Matthiessen
authors.forename: O
authors.initials: O
authors.lastname: Zeitz
authors.forename: G
authors.initials: G
authors.lastname: Richard
authors.forename: M
authors.initials: M
authors.lastname: Klemm
mesh_terms: D001783:Blood Flow Velocity; D019842:Ciliary Arteries / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005901:Glaucoma / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D009880:Ophthalmic Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011673:Pulsatile Flow; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D018615:Ultrasonography, Doppler, Color / Q000379:methods; D014655:Vascular Resistance