Angiography of the retina and the choroid with phase-resolved OCT using interval-optimized backstitched B-scans

Boy Braaf, Koenraad A Vermeer, Kari V Vienola, Johannes F de Boer

Research output: Contribution to journalArticleResearchpeer-review


In conventional phase-resolved OCT blood flow is detected from phase changes between successive A-scans. Especially in high-speed OCT systems this results in a short evaluation time interval. This method is therefore often unable to visualize complete vascular networks since low flow velocities cause insufficient phase changes. This problem was solved by comparing B-scans instead of successive A-scans to enlarge the time interval. In this paper a detailed phase-noise analysis of our OCT system is presented in order to calculate the optimal time intervals for visualization of the vasculature of the human retina and choroid. High-resolution images of the vasculature of a healthy volunteer taken with various time intervals are presented to confirm this analysis. The imaging was performed with a backstitched B-scan in which pairs of small repeated B-scans are stitched together to independently control the time interval and the imaged lateral field size. A time interval of ≥ 2.5 ms was found effective to image the retinal vasculature down to the capillary level. The higher flow velocities of the choroid allowed a time interval of 0.64 ms to reveal its dense vasculature. Finally we analyzed depth-resolved histograms of volumetric phase-difference data to assess changes in amount of blood flow with depth. This analysis indicated different flow regimes in the retina and the choroid.

Original languageEnglish
Pages (from-to)20516-34
Number of pages19
JournalOptics Express
Issue number18
Publication statusPublished - 27 Aug 2012


  • Algorithms
  • Angiography/instrumentation
  • Ciliary Arteries/anatomy & histology
  • Humans
  • Image Enhancement/instrumentation
  • Reproducibility of Results
  • Retinal Vessels/anatomy & histology
  • Retinoscopes
  • Sensitivity and Specificity
  • Tomography, Optical Coherence/instrumentation


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