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Leo Puyo, Michel Paques, Mathias Fink, Jose Alain Sahel, Michael Atlan; Laser Doppler holography to analyze the flow in the deep choroidal vasculature. Invest. Ophthalmol. Vis. Sci. 2019;60(9):4750.
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© ARVO (1962-2015); The Authors (2016-present)
The choroid is a highly vascularized tissue whose implication in retinal diseases is gaining increasing interest. Despite its critical importance, the choroid is not fully understood yet as investigating its anatomy and flow remains challenging because of the optical barrier formed by the photoreceptors and melanin in the retinal pigment epithelium. We here report on using laser Doppler holography to study the choroidal vasculature non-invasively.
Laser Doppler holography is a full-field angiographic technique that we previously used to image retinal blood flow at 785 nm with a temporal resolution of just a few ms. Holograms are recorded at 60 kHz and power Doppler images are obtained with a Fourier analysis of the Doppler power spectral density. Owing to this ability to select strongly Doppler shifted light, we were able to reveal choroidal vessels where the flow greater than in the retina. Additionally, we have compared our results to SS-OCT (Zeiss - Plex Elite 9000) and ICG angiography (Heidelberg – Spectralis).
We have found that laser Doppler holography was able to reveal choroidal vascular structures that were not observed with OCT nor ICG-A. The instrument is especially sensitive to large blood flows and thus preferentially reveals choroidal arteries. Finally, furthering the Fourier analysis of the Doppler spectrum allows to separate vessels according to their flows which offers the possibility to discriminate arteries from veins in the choroid.
Laser Doppler holography can non-invasively reveal choroidal structures in the deep choroid, particularly in the macular region despite the high density of photoreceptors. Additionally, because there are large differences of blood flow in the choroid between arteries and veins, and because laser Doppler holography allows to make quantitative measurements of blood flow in the choroid, we have been able to propose a process to differentiate arteries and veins in the choroid.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
Multimodal imaging of a same region of interest. (a) Scanning laser ophthalmoscope. (b) en-face swept-source OCT. (c) ICG-angiography. (d) Low frequency power Doppler image. (e) High frequency power Doppler image. (f) Power Doppler color composite image of (d) and (e), showing vessels with low and large flows in cyan and red, respectively.
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