Optimal wavelengths for subdiffuse scanning laser oximetry of the human retina

Mathi Damodaran*, Arjen Amelink, Johannes F. De Boer

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Retinal blood vessel oxygenation is considered to be an important marker for numerous eye diseases. Oxygenation is typically assessed by imaging the retinal vessels at different wavelengths using multispectral imaging techniques, where the choice of wavelengths will affect the achievable measurement accuracy. Here, we present a detailed analysis of the error propagation of measurement noise in retinal oximetry, to identify optimal wavelengths that will yield the lowest uncertainty in saturation estimation for a given measurement noise level. In our analysis, we also investigate the effect of hemoglobin packing in discrete blood vessels (pigment packaging), which may result in a nonnegligible bias in saturation estimation if unaccounted for under specific geometrical conditions, such as subdiffuse sampling of smaller blood vessels located deeper within the retina. Our analyses show that using 470, 506, and 592 nm, a fairly accurate estimation of the whole oxygen saturation regime [0 1] can be realized, even in the presence of the pigment packing effect. To validate the analysis, we developed a scanning laser ophthalmoscope to produce high contrast images with a maximum pixel rate of 60 kHz and a maximum 30-deg imaging field of view. Confocal reflectance measurements were then conducted on a tissue-mimicking scattering phantom with optical properties similar to retinal tissue including narrow channels filled with absorbing dyes to mimic blood vessels. By imaging at three optimal wavelengths, the saturation of the dye combination was calculated. The experimental values show good agreement with our theoretical derivations.

Original languageEnglish
Article number086003
Pages (from-to)1-15
Number of pages16
JournalJournal of Biomedical Optics
Volume23
Issue number8
Early online date27 Aug 2018
DOIs
Publication statusPublished - Aug 2018

Funding

This research was funded by the Netherlands Organisation for Scientific Research (NWO) with a Vici (JFdB) (Grant No. 91810628), the Netherlands Organisation for Health Research and Development ZonMW (Grant No. 91212061), and STW (Grant No. 12822), which are both a part of NWO, and Heidelberg Engineering GmbH. The authors would like to thank F. Feroldi, M.G.O. Grafe, L. Bartolini, and Dr. B. K. P. Lochocki for assistance with experiments; J. J. A. Weda for fabrication of the phantoms.

FundersFunder number
Heidelberg Engineering GmbH
Netherlands Organisation for Health Research and Development ZonMW91212061
Nederlandse Organisatie voor Wetenschappelijk Onderzoek91810628
Stichting voor de Technische Wetenschappen12822

    Keywords

    • blood vessel diameter
    • hemoglobin
    • oxygen saturation
    • phantoms
    • retinal oximetry
    • scanning laser ophthalmoscope

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