Quantitative retinal blood flow velocity map and macular blood flow.

<p>(A) The retina of a healthy subject imaged using the RFI device with a field of view of 20-degrees (4.3 × 4.3 mm²) centered on the fovea (dark area in the center) is shown. The arterioles are marked in red and overlaid with the measured blood flow velocities (mm/s); the venules and their respective velocities are marked in pink. The measured vessels cover the second, third and fourth branches of the retinal vessels. A negative value indicates blood flow away from the heart. In this case, the arteriolar flow moved towards to the fovea. A positive value indicates blood flow towards to the heart. In this case, the vessels are venules. (B) To analyze the macular blood flow, supplying the macular region including the vascular zone of the fovea, a 2.3 mm circle (blue) centered on the fovea was drawn and vessel diameters were measured in vessels at the locations (yell and green dots) crossing the circle. The diameter of the vessels which crossed the circle was determined. Blood flow of the vessel segment was calculated using the measured velocity and diameter for each arteriole (yellow dot) or venule (green dot). The total macular flow was the sum of all flow rates in the arterioles (all yellow dots) and venules (all green dots) which crossed the circle. The total macular flow rate of this healthy subject was 3.7 nl/s in the arterioles and 3.5 nl/s in the venules. Bar = 500 μm.