Abstract
Purpose :
To evaluate the reliability of speckle-based flow measurements in retinal vessels of normal subjects using optical coherence tomography (OCT) and explore the use of this methodology in eyes with disease.
Methods :
Blood flow in retinal vessels was analyzed using high versus low spatial frequency components in selected areas with a modified Maestro2 (Topcon Healthcare, Tokyo, Japan), across 6 cardiac cycles in 8 subjects from scans without significant eye movements. Intraclass correlation coefficients (ICC) were calculated with two-way random effects for absolute agreement, assessing flow in superotemporal arcade arteries and veins. Mean flow was derived as the average peak and trough flow of the same cycle, expressed in relative units. ICC values categorized reliability as poor (<0.5), moderate (0.5-0.75), good (0.75-0.9), and excellent (>0.9). The methodology was also applied to diseased eyes.
Results :
In the normal subjects, the mean peak flow in arteries, representing the maximal flow during systole, was 463(± 27.4] while the trough, which was the lowest flow during diastole, was 338 (±37.7) in arteries, for a ratio of 1.38. Corresponding values in the veins were 362 (±25.7) and 328 (±20.2), and a ratio of 1.1. The ICCs were 0.5 for single measurements and 0.86 for average measurements for the arterial peak flow, and 0.64 and 0.92 for single and average trough arterial flow measurements, respectively. For veins the peak flow ICC was 0.88 for single and 0.98 for average measurements and for trough flow 0.8 for single and 0.97 for average measurements. The mean flow had an ICC of 0.71 for single and 0.94 for average measurements for arterial flow and 0.68 and 0.93 for venous flow.
Conclusions :
Single measurement reliability of arterial flow had moderate reliability for peak and trough flow values, and good to excellent reliability for average measurements. Venous flow showed good reliability for peak and trough single measurements, and excellent reliability for average measurements. Mean flow values were moderate for single measures and excellent for average measurements. This approach enables non-invasive blood flow measurement within the eye, applicable to both health and disease states using conventional OCT. Detailed clinical case studies demonstrating OCT blood flow measurement will be discussed.
This abstract was presented at the 2024 ARVO Imaging in the Eye Conference, held in Seattle, WA, May 4, 2024.