title: Segmental reproducibility of retinal blood flow velocity measurements using retinal function imager.
abstract: BACKGROUND
  To evaluate the reproducibility of blood flow velocity measurements of individual retinal blood vessel segments using retinal function imager (RFI).
  
  
  METHODS
  Eighteen eyes of 15 healthy subjects were enrolled prospectively at three centers. All subjects underwent RFI imaging in two separate sessions 15 min apart by a single experienced photographer at each center. An average of five to seven serial RFI images were obtained. All images were transferred electronically to one center, and were analyzed by a single observer. Multiple blood vessel segments (each shorter than 100 μm) were co-localized on first and second session images taken at different times of the same fundus using built-in software. Velocities of corresponding segments were determined, and then the inter-session reproducibility of flow velocity was assessed by the concordance correlation co-efficient (CCC), coefficient of reproducibility (CR), and coefficient of variance (CV).
  
  
  RESULTS
  Inter-session CCC for flow velocity was 0.97 (95% confidence interval (CI), 0.966 to 0.9797). The CR was 1.49 mm/sec (95% CI, 1.39 to 1.59 mm/sec), and CV was 10.9%. The average arterial blood flow velocity was 3.16 mm/sec, and average venous blood flow velocity was 3.15 mm/sec. The CR for arterial and venous blood flow velocity was 1.61 mm/sec and 1.27 mm/sec respectively.
  
  
  CONCLUSIONS
  RFI provides reproducible measurements for retinal blood flow velocity for individual blood vessel segments, with 10.9% variability.
authors.affiliation: Jacobs Retina Center at Shiley Eye Center, University of California, San Diego, 9415 Campus Point Drive, MC 0946, La Jolla, CA, 92093-0946, USA.
authors.forename: Jay
authors.initials: J
authors.lastname: Chhablani
authors.forename: Dirk-Uwe
authors.initials: DU
authors.lastname: Bartsch
authors.forename: Lingyun
authors.initials: L
authors.lastname: Cheng
authors.forename: Laura
authors.initials: L
authors.lastname: Gomez
authors.forename: Rayan A
authors.initials: RA
authors.lastname: Alshareef
authors.forename: Sami S
authors.initials: SS
authors.lastname: Rezeq
authors.forename: Sunir J
authors.initials: SJ
authors.lastname: Garg
authors.forename: Zvia
authors.initials: Z
authors.lastname: Burgansky-Eliash
authors.forename: William R
authors.initials: WR
authors.lastname: Freeman
mesh_terms: D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D003952:Diagnostic Imaging / Q000295:instrumentation*; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D004912:Erythrocytes / Q000502:physiology; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012039:Regional Blood Flow / Q000502:physiology*; D015203:Reproducibility of Results; D012171:Retinal Vessels / Q000502:physiology*; D055815:Young Adult