Abstract
Purpose :
To evaluate the ability to measure pulsatile retinal blood flow using structural optical coherence tomography (OCT) scans. To compare OCT speckle-based flow measurements in retinal vessels of normal subjects to those obtained using Doppler OCT analysis.
Methods :
Measurements of pulsatile retinal blood flow were obtained on normal subjects both at rest and after exertion. Repeated OCT scans were acquired using a Maestro2 instrument (Topcon Healthcare, Tokyo, Japan) with modified scan software. The OCT scans were obtained over ~1 mm expanse with a B-scan rate of approximately 45 Hz for ~2 seconds. All OCT images were registered to each other to reduce motion artifacts. Each OCT scan underwent processing to generate a conventional structural OCT image and a phase velocity image through Doppler OCT analysis.
A region of interest was selected over a retinal vessel for each series of structural and phase velocity image pairs. The pulsatile blood flow can be derived by calculating the speckle density values in the region of interest of the structural OCT images. In addition, the pulsatile retinal blood flow can also be calculated as the mean flow velocity in the region of interest of the phase velocity images.
Results :
The pulsatile retinal blood flow obtained by speckle analysis and Doppler OCT analysis resemble each other in normal subjects both at rest and after exertion. Speckle density increases during systole corresponding to an increase in the mean flow velocity of Doppler OCT while the speckle density decreases during diastole corresponding to a similar decrease in the mean flow velocity. Figure 1 shows the different blood flow profiles calculated using either Doppler OCT or speckle-based analysis.
Conclusions :
We have shown that measurements of the retinal blood flow profiles can be obtained using speckle-based analysis of structural OCT images. This simple method could allow non-invasive pulsatile retinal blood flow measurements in the clinic using conventional OCT instruments.
This abstract was presented at the 2024 ARVO Imaging in the Eye Conference, held in Seattle, WA, May 4, 2024.