June 2023
Volume 64, Issue 9
Open Access
ARVO Imaging in the Eye Conference Abstract  |   June 2023
Retinal capillary velocimetry based on optical coherence tomography angiography scan protocols
Author Affiliations & Notes
  • Yuxin Xia
    Bioengineering, University of Washington, Seattle, Washington, United States
  • Xiao Zhou
    Bioengineering, University of Washington, Seattle, Washington, United States
  • Zahra Nafar
    Carl Zeiss Meditec, Inc., Dublin, California, United States
  • Qinqin Zhang
    Carl Zeiss Meditec, Inc., Dublin, California, United States
  • Giovanni Gregori
    Bascom Palmer Eye Institute, Miami, Florida, United States
  • Philip J. Rosenfeld
    Bascom Palmer Eye Institute, Miami, Florida, United States
  • Amir H Kashani
    Department of Ophthalmology, Johns Hopkins University, Maryland, United States
  • Kasra Rezaei
    Department of Ophthalmology, University of Washington, Seattle, Washington, United States
  • Ruikang Wang
    Bioengineering, University of Washington, Seattle, Washington, United States
    Department of Ophthalmology, University of Washington, Seattle, Washington, United States
  • Footnotes
    Commercial Relationships   Yuxin Xia, None; Xiao Zhou, None; Zahra Nafar, Carl Zeiss Meditec Inc. (E); Qinqin Zhang, Carl Zeiss Meditec Inc. (E); Giovanni Gregori, Carl Zeiss Meditec Inc. (F); Philip J. Rosenfeld, Alexion (F), Annexon (C), Apellis (C), Apellis (I), Bayer (C), Boehringer-Ingelheim (C), Carl Zeiss Meditec (C), Carl Zeiss Meditec (F), Chengdu Kanghong Biotech (C), Gyroscope Therapeutics (F), InflammX (C), Ocudyne (C), Ocudyne (I), Regeneron (C), Stealth BioTherapeutics (F), Unity Biotechnology (C), Valitor (I), Verana Health (I); Amir Kashani, Carl Zeiss Meditec Inc. (F), Carl Zeiss Meditec Inc. (C); Kasra Rezaei, None; Ruikang Wang, Carl Zeiss Meditec (F), Carl Zeiss Meditec (C), Colgate Palmolive Company (F), Estee Lauder Inc (F)
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science June 2023, Vol.64, PB0070. doi:
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      Yuxin Xia, Xiao Zhou, Zahra Nafar, Qinqin Zhang, Giovanni Gregori, Philip J. Rosenfeld, Amir H Kashani, Kasra Rezaei, Ruikang Wang; Retinal capillary velocimetry based on optical coherence tomography angiography scan protocols. Invest. Ophthalmol. Vis. Sci. 2023;64(9):PB0070.

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

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Abstract

Purpose : To develop a capillary velocimetry strategy to map blood flow velocities in retinal capillary beds and choriocapillaris using swept-source optical coherence tomography angiography (SS-OCTA).

Methods : OCT images were acquired by a 1050 nm center wavelength swept source OCTA machine (PLEX® Elite 9000, ZEISS, Dublin, CA) operating at 200 kHz A-line rate with motion tracking mechanism and 2x2mm scan pattern. A new B-M scan protocol with a 1ms time delay between consecutive B scans has been incorporated into the system, enabling the measurement of flow velocities ranging from 0 mm/s to 0.5 mm/s. A method based on eigendecomposition was developed to determine the blood flow velocity in capillary vessels after static tissue signals were eliminated using an adaptive regression filter (motion tolerative). The mean velocity of blood flow was represented by the signal's mean frequency, which was estimated using the first lag one autocorrelation of corresponding eigenvectors. The scans were segmented into the superficial retinal layer (SRL), deep retinal layer (DRL), and choriocapillaris (CC) layers in order to explore the speed variations in various plexus. Blood flow speed variations determined by the eigenvalues in each layer were presented. Vessels larger than 30 microns were removed from the analyses.

Results : Normal eyes (N=55) with a wide age range from 20 to 90 years old were recruited in the study. The results indicate that at the same age range, the capillary flows in the SRL are faster but more heterogeneous than that in the DRL. Choriocapillaris flow is highest in the central fovea region and slightly reduced towards the periphery. The capillary flow in all the layers analyzed exhibits age dependence, i.e., decreases with increasing age, and this dependence is strongest in the superficial capillary plexus.

Conclusions : The proposed strategy demonstrates important quantifiable information on blood flow speeds within the retinal capillaries in normal eyes. This method of measuring capillary velocimetry may contribute to the study of age-related variations in normal eyes and to the advancement of knowledge regarding ocular diseases.

This abstract was presented at the 2023 ARVO Imaging in the Eye Conference, held in New Orleans, LA, April 21-22, 2023.

 

Fig 1. An example of mean frequency (MF) calculated by ED velocimetry approach compared with OCTA enface images.

Fig 1. An example of mean frequency (MF) calculated by ED velocimetry approach compared with OCTA enface images.

 

Figure 2. Relationship between the MF and age in Retinal and choroidal layers. (A) superficial retina layer, (B) deep retina layer, (C) choriocapillaris layer.

Figure 2. Relationship between the MF and age in Retinal and choroidal layers. (A) superficial retina layer, (B) deep retina layer, (C) choriocapillaris layer.

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