June 2022
Volume 63, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2022
Capillary velocimetry on human retina---a preliminary study
Author Affiliations & Notes
  • Qinqin Zhang
    University of Washington, Seattle, Washington, United States
  • Xiao Zhou
    University of Washington, Seattle, Washington, United States
  • Ruikang K Wang
    University of Washington, Seattle, Washington, United States
  • Footnotes
    Commercial Relationships   Qinqin Zhang None; Xiao Zhou None; Ruikang Wang Carl Zeiss Meditec, Code C (Consultant/Contractor), Carl Zeiss Meditec, Code F (Financial Support), Carl Zeiss Meditec, Code P (Patent)
  • Footnotes
    Support  NIH Grant EY28753, EY01481, Carl Zeiss Meditec., Research to Prevent Blindness
Investigative Ophthalmology & Visual Science June 2022, Vol.63, 3510. doi:
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      Qinqin Zhang, Xiao Zhou, Ruikang K Wang; Capillary velocimetry on human retina---a preliminary study. Invest. Ophthalmol. Vis. Sci. 2022;63(7):3510.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose : To investigate the capillary blood flow velocity on human retina with various pathologies in vivo based on commercial OCTA device with modified scanning protocols

Methods : A 1060 nm SS OCTA engine (PLEX® Elite 9000, ZEISS, Dublin, CA) with 200 kHz A-line rate and motion tracking mechanism was utilized in our study. New scanning protocol with 200 A-linesx200 B-scans covering ~ 2mmx2mm with 10 repetitions was designed and implemented on the device for capillary velocimetry estimation. The time interval between the adjacent B scans was ~1ms that gives a distinguishable velocity range from 0 mm/s to ~0.5mm/s according to the theorical analysis. The mean frequency (MF) of signal was calculated by eigen-decomposition (ED) approach representing the mean velocity of blood flow within the scanned tissue volume. Depth-resolved retinal and choroidal layers were segmented to investigate the speed variations in different plexus, including the superficial retinal layer (SRL), deep retinal layer (DRL), and choriocapillaris (CC) layers. Color images were utilized to demonstrate the flow speed with red-ish color indicating the fast flow, and blue-ish color indicating the slow flow. To keep the consistency, a fixed display range ([0, 700 Hz]) was applied to all the color images, which was only determined by the time interval of the scanning protocol.

Results : Ten normal eyes (mean age 27.7±3.3), twelve NPDR eyes (mean age 57.2±5.9) and twenty PDR eyes (mean age 56.2±16.6) were recruited in this preliminary study. The MF has shown the capability of differentiating the flow speed at capillary level (Fig.1) in human retina. Overall, the capillaries in retinal layers (SRL&DRL) showed a larger mean MF compared with the flow in CC layer both in normal and DR eyes. A significantly deceased flow speed was observed in PDR eyes by one-anova test among the three groups. However, the ages were not age-matched among the three groups which may introduce bias in the flow speed comparison. Age-matched normal eyes are required for further comparison.

Conclusions : The modified scanning protocol in PLEX Elite with a time interval of ~ 1ms has the capability to differentiate the blood flow speed of capillaries in human eyes with various ocular pathologies using the ED-based capillary velocimetry approach. The results showed the velocimetry may play a role not only in the investigations of ocular disease but also in developing endpoints for therapeutic clinical trials.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.



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