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Br J Ophthalmol 2004;88:348-353 doi:10.1136/bjo.2003.024885
  • Clinical science
    • Scientific reports

Reproducibility of circadian retinal and optic nerve head blood flow measurements by Heidelberg retina flowmetry

  1. C P Jonescu-Cuypers1,2,
  2. A Harris2,
  3. K U Bartz-Schmidt3,
  4. L Kagemann2,
  5. A S Boros1,
  6. U E Heimann1,
  7. B H Lenz1,
  8. R-D Hilgers4,
  9. G K Krieglstein1
  1. 1Department of Ophthalmology, University of Cologne, Cologne, Germany
  2. 2Glaucoma Research and Diagnostic Center, Department of Ophthalmology, University of Indiana, Indianapolis, USA
  3. 3Department of Ophthalmology, University of Tübingen, Tübingen, Germany
  4. 4Institute for Biometry, University of Aachen (RWTH), Aachen, Germany
  1. Correspondence to: Dr Christian P Jonescu-Cuypers Laboratory of Biomorphometry and Retinal Perfusion Analysis, Joseph-Stelzmann-Strasse 9, 50924 Cologne, Germany; aia12uni-koeln.de
  • Accepted 15 July 2003

Abstract

Background/aim: The Heidelberg retina flowmeter (HRF) is designed to measure retinal capillary blood flow. Previous studies however showed weak reproducibility of data. The intraindividual reproducibility of circadian HRF measurements was examined in healthy subjects in three locations of the retina.

Methods: 36 healthy volunteers (27.3 (SD 4.3) years) were examined by HRF seven times a day (t0–t6). Using a default window of 10×10 pixels, three consecutive measurements were performed in three precise focusing planes: superficial, intermediate and deep layer, peripapillary retina, neuroretinal rim and cup, respectively. Images of identical tissue locations identified by capillary landmarks of each layer were selected to quantify the retinal microcirculation of each volunteer. Means and standard deviations of all flow results of a given subject were calculated, at t0–t6 and the coefficients of variation as a measure of reproducibility.

Results: The coefficients of variation ranged between 8.4% and 41.0% in the superficial layer (mean 19.8% (SD 8.4%)), 10.6%, and 43.0% in the intermediate layer (mean 24.0% (SD 8.4%)), and 9.9% and 84.0% (mean 29.6% (SD 15.8%)) in the deep layer.

Conclusions: These data show the best reproducibility of measurements in the superficial layer followed by the intermediate and the deep layer. Clinically, this is an unsatisfactory intraindividual reproducibility of flow values in each studied layer.

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