April 2014
Volume 55, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2014
Quantitatively evaluating retinal capillary flow using Optical micro-angiography
Author Affiliations & Notes
  • Lin An
    Bioengineering, University of Washington, Seattle, WA
  • Murray A Johnstone
    ophthalmology, University of Washington, Seattle, WA
  • Ruikang K Wang
    Bioengineering, University of Washington, Seattle, WA
    ophthalmology, University of Washington, Seattle, WA
  • Footnotes
    Commercial Relationships Lin An, None; Murray Johnstone, None; Ruikang Wang, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 4329. doi:
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      Lin An, Murray A Johnstone, Ruikang K Wang; Quantitatively evaluating retinal capillary flow using Optical micro-angiography. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4329.

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

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Abstract
 
Purpose
 

To explore the feasibility of an optical micro-angiography (OMAG) technique to evaluate human retinal capillary flow in vivo.

 
Methods
 

A repeated B-scan scanning pattern was designed to quantify retinal capillary flow. If a red blood cell (RBC) passes through a capillary, the light backscattered from it appears as a bright spot in the OMAG image. If the capillary is sequentially imaged over time, the backscattered light from the RBC’s then appears as intensity peaks over the time. The peak width can represent the time a single RBC passesing through the imaging beam while the peak numbers over the time period depict blood flux.

 
Results
 

Fig.1 (a) and (b) are a typical B-scan microstructure image and the corresponding blood flow image. Fig.1 (c) and (d) presents a series of magnified microstructural images and corresponding blood flow images. At the time point 1, Fig.1 (d.i) doesn't show any RBC signal. (d.ii) to (d.v) are the dynamic sequential flow images showing an RBC passing through a capillary. (d.vi) demonstrate that the RBC has left the imaging beam. Assuming the diameters of the RBC and imaging beam are both 5 micros, the velocity is then ~ 400 micros/s. Fig. 2 (a) and (b) are the intensity profiles of two typical capillaries, where the evaluated velocities of RBC are given along with peak signals. By counting the peak numbers, the RBC flux is quantified. The number flux of V1 and V2 are ~ 24/s and ~19/s. We imaged five locations peripheral to fovea. The velocity and flux of the selected capillaries were averaged and compared. The results are demonstrated in Fig.2 (c) and (d), indicating that the RBC velocity and the capillary flux are similar at three retinal layers.

 
Conclusions
 

We demonstrate that the OMAG is capable of quantitatively evaluating retinal capillary blood flow. We found that there is no significant difference between RBC velocity and flux passing through capillaries located at different layers peripheral to the fovea.

 
 
Fig. 1. (a) Typical cross sectional structure images; (b) the corresponding 2D cross sectional OMAG blood flow image. (c) sequential microstructural images for the location marked in (a); (d) the corresponding sequential blood flow images.
 
Fig. 1. (a) Typical cross sectional structure images; (b) the corresponding 2D cross sectional OMAG blood flow image. (c) sequential microstructural images for the location marked in (a); (d) the corresponding sequential blood flow images.
 
 
Fig.2. (a) & (b) are the intensity profiles of V1 and V2; (c) represent the average RBC velocities and standard deviations of three retinal layers; (d) the average capillary flux and standard deviations of three retinal layers.
 
Fig.2. (a) & (b) are the intensity profiles of V1 and V2; (c) represent the average RBC velocities and standard deviations of three retinal layers; (d) the average capillary flux and standard deviations of three retinal layers.
 
Keywords: 436 blood supply • 688 retina  
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