Purchase this article with an account.
Rene M. Werkmeister, Nikolaus Dragostinoff, Leopold Schmetterer; Absolute Retinal Blood Flow Measurement by Dual-beam Bidirectional Doppler Fourier-domain Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6028.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To evaluate the ability of a dual-beam bidirectional Doppler Fourier-domain (FD) optical coherence tomography (FD-OCT) system to measure absolute flow velocities v and absolute blood flow Q in human retinal vessels.
Single beam Doppler OCT systems enable only for the measurement of relative blood flow velocities and blood flow values or require extraction of the Doppler angle from multiple A scans. Contrary to this, in our system the sample is illuminated by two beams, spanning a detection plane, in which the magnitude of the velocity can be assessed without knowledge of the Doppler angle. Via an SLO image acquired with the same device, the orientation of the velocity vector with respect to the detection plane is determined. Thus, the absolute velocity can be calculated.
The accuracy and reproducibility of the OCT device has been evaluated by in vitro experiments with diluted milk. The flow was driven by a syringe pump through a capillary with an inner diameter of 300 µm. For the preset flow velocities (0.8 - 40 mm/s) we found an entirely linear behavior of the estimated values. The mean coefficient of variation c (standard deviation/mean) was found to be 0.055. Furthermore, blood flow measurements in venous bifurcations of healthy human volunteers were performed. For this purpose, the mean flow velocity was measured with the Dual-beam FD-OCT system, while the vessel diameters D were determined by means of a Retinal Vessel Analyzer (Imedos, Germany). Both flow velocities and flow values were in the same range as previously published data - we found vmean between 5.2 and 12.2 mm/s for D ranging from 84 - 172 µm. The coefficient of variation c for the blood flow estimation ranged from 0.04 to 0.06. Furthermore, the sums of the flows in the two source vessels before the venous junction were in good agreement with the flow in the vessel after the junction, i.e. Q1 + Q2 = Q3. The mean deviation for five examined junctions was 5.5 percent.
The dual-beam Doppler FD-OCT system allows for measurement of absolute flow velocities in retinal vessels with high accuracy and reproducibility. The system could serve as a helpful tool for the study and diagnostics of several retinal diseases related to the retinal perfusion, e.g. diabetic retinopathy or branch retinal vein occlusion.
This PDF is available to Subscribers Only