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Original Investigation
October 2016

Estimating Retinal Blood Flow Velocities by Optical Coherence Tomography

Author Affiliations
  • 1Department of Ophthalmology, Medical University of Graz, Graz, Austria
  • 2Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
  • 3Institute for Medical Informatics, Statistics and Documentation, Medical University of Graz, Graz, Austria
  • 4Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
JAMA Ophthalmol. 2016;134(10):1104-1110. doi:10.1001/jamaophthalmol.2016.2507
Key Points

Question  Can retinal blood flow velocity be estimated from structural optical coherence tomographic scans?

Findings  In this cross-sectional study of 30 eyes from 30 patients, retinal blood flow velocity could be visually graded as low, medium, or high flow velocity via assessment of the intraluminal backscattering pattern on optical coherence tomography by 3 independent graders. When discriminating low flow velocities from medium or high flow velocities, sensitivity ranged from 88.2% to 100% and specificity ranged from 97.6% to 100%.

Meaning  These data suggest that a low retinal blood flow velocity reflects in a visually distinct contrast reduction of the intraluminal pattern of retinal vessels on optical coherence tomography.

Abstract

Importance  While optical coherence tomography (OCT) angiography has been considered to evaluate retinal capillary blood flow instead of fluorescein angiography, the reflectance pattern of blood vessels on structural OCT might also provide retinal capillary flow data in the absence of fluorescein angiography. This potential has been insufficiently explored, despite promising data concerning a possible relationship between the reflectance pattern of blood vessels and their perfusion velocity in a laboratory setting.

Objective  To evaluate the potential of retinal blood flow velocity estimation by structural OCT.

Design, Setting, and Participants  Cross-sectional observational study conducted from June to November 2015 at a tertiary clinical referral center. Sixty arteries (the superior and inferior temporal arteries) from 30 eyes of 30 patients (17 female, 13 male) were included in the study.

Main Outcomes and Measures  Based on the intraluminal contrast patterns of retinal arteries on OCT, 3 independent graders categorized the blood flow velocities as low, medium, or high. These results and the results from a software-based intraluminal contrast analysis were compared with the retinal blood flow velocities measured by video fluorescein angiography.

Results  Among the 30 eyes of 30 patients (mean [SD] age, 72.6 [12.3] years; 17 female, 13 male), 15 were controls without retinal occlusion, 6 had a branch retinal artery occlusion, and 9 had a central retinal artery occlusion. When discriminating between low flow velocities and medium or high flow velocities, the graders’ sensitivity ranged from 88.2% to 100% (grader 1: 88.2%; 95% CI, 63.6%-98.5%; grader 2: 88.2%; 95% CI, 63.6%-98.5%; and grader 3: 100%; 95% CI, 69.8%-100%) and their specificity ranged from 97.6% to 100% (grader 1: 100%; 95% CI, 87.7%-100%; grader 2: 97.6%; 95% CI, 87.4%-99.9%; and grader 3: 100%; 95% CI, 87.7%-100%). The κ coefficients of the comparison between the 3 graders and the angiography were 0.77 (95% CI, 0.60-0.93; P < .001), 0.64 (95% CI, 0.44-0.83; P < .001), and 0.87 (95% CI, 0.74-0.99; P < .001). In the computer-based assessment, the contrast reduction of the intraluminal pattern could be numerically expressed in a specific coefficient in the model (I2, describing the angular change of the backscattering intensity in the model), which presented nonoverlapping intervals between low flow velocities and medium or high flow velocities (mean [SD] I2, 0.3 [5.3], 20.4 [6.4], and 21.7 [4.0], respectively).

Conclusions and Relevance  This study suggests that a low retinal blood flow velocity reflects in a visually distinct contrast reduction of the intraluminal pattern of retinal vessels on OCT. Larger studies are required to assess the clinical benefits.

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