Directional optical coherence tomography reveals melanin concentration-dependent scattering properties of retinal pigment epithelium

Ratheesh K. Meleppat, Pengfei Zhang, Myeong Jin Ju, Suman K. Manna, Yifan Jian, Edward N. Pugh, Robert J. Zawadzki

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


Optical coherence tomography (OCT) is a powerful tool in ophthalmology that provides in vivo morphology of the retinal layers and their light scattering properties. The directional (angular) reflectivity of the retinal layers was investigated with focus on the scattering from retinal pigment epithelium (RPE). The directional scattering of the RPE was studied in three mice strains with three distinct melanin concentrations: albino (BALB/c), agouti (129S1/SvlmJ), and strongly pigmented (C57BL/6J). The backscattering signal strength was measured with a directional OCT system in which the pupil entry position of the narrow OCT beam can be varied across the dilated pupil of the eyes of the mice. The directional reflectivity of other retinal melanin-free layers, including the internal and external limiting membranes, and Bruch's membrane (albinos) were also measured and compared between the strains. The intensity of light backscattered from these layers was found highly sensitive to the angle of illumination, whereas the inner/outer segment (IS/OS) junctions showed a reduced sensitivity. The reflections from the RPE are largely insensitive in highly pigmented mice. The differences in directional scattering between strains shows that directionality decreases with an increase in melanin concentrations in RPE, suggesting increasing contribution of Mie scattering by melanosomes.

Original languageEnglish (US)
Article number066011
JournalJournal of biomedical optics
Issue number6
StatePublished - Jun 30 2019
Externally publishedYes


  • directional scattering
  • melanin
  • optical coherence tomography
  • retinal imaging
  • retinal pigment epithelium

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Biomedical Engineering


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