Why choroid vessels appear dark in clinical OCT images

Mitchell A. Kirby, Chenxi Li, Woo June Choi, Giovanni Gregori, Philip J Rosenfeld, Ruikang Wang

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Scopus citations


With the onset of clinically available spectral domain (SD-OCT) and swept source (SS-OCT) systems, clinicians are now easily able to recognize sub retinal microstructure and vascularization in the choroidal and scleral regions. As the bloodrich choroid supplies nutrients to the upper retinal layers, the ability to monitor choroid function accurately is of vital importance for clinical assessment of retinal health. However, the physical appearance of the choroid blood vessels (darker under a healthy Retinal Pigmented Epithelium (RPE) compared to regions displaying an RPE atrophic lesion) has led to confusion within the OCT ophthalmic community. The differences in appearance between each region in the OCT image may be interpreted as different vascular patterns when the vascular networks are in fact very similar. To explain this circumstance, we simulate light scattering phenomena in the RPE and Choroid complexes using the finite difference time domain (FDTD) method. The simulation results are then used to describe and validate imaging features in a controlled multi-layered tissue phantom designed to replicate human RPE, choroid, and whole blood microstructure. Essentially, the results indicate that the strength of the OCT signal from choroidal vasculature is dependent on the health and function of the RPE, and may not necessarily directly reflect the health and function of the choroidal vasculature.

Original languageEnglish (US)
Title of host publicationOphthalmic Technologies XXVIII
ISBN (Electronic)9781510614338
StatePublished - Jan 1 2018
Event28th Conference on Ophthalmic Technologies - San Francisco, United States
Duration: Jan 27 2018Jan 28 2018


Other28th Conference on Ophthalmic Technologies
CountryUnited States
CitySan Francisco


  • Finite Difference Time Domain
  • light scattering anisotropic factor
  • Mie scattering theory
  • Optical coherence tomography

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Biomaterials
  • Radiology Nuclear Medicine and imaging

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  • Cite this

    Kirby, M. A., Li, C., Choi, W. J., Gregori, G., Rosenfeld, P. J., & Wang, R. (2018). Why choroid vessels appear dark in clinical OCT images. In Ophthalmic Technologies XXVIII (Vol. 10474). [1047428] SPIE. https://doi.org/10.1117/12.2291057