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R. M. Werkmeister, N. Dragostinoff, T. Schmoll, L. Schmetterer; Measurement of Absolute Flow Velocities by Dual-Beam Bidirectional Fourier-Domain Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5005.
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© ARVO (1962-2015); The Authors (2016-present)
To measure absolute flow velocities in vitro in glass capillaries and in vivo in human retinal vessels by dual-beam bidirectional Fourier-domain (FD) optical coherence tomography (FD-OCT).
With conventional Doppler OCT techniques the magnitude of the velocity vector can only be determined from a single measurement if the projection of the probe beam in the retinal plane and the velocity vector of interest are collinear and the Doppler angle is known. This condition, however, is not fulfilled when measurements are performed in the ocular fundus, where the Doppler angle is unknown. To overcome this problem, we illuminate the eye with two probe beams, separated by their polarization properties, allowing for measurement of the velocity vector’s magnitude in the detection plane spanned by the incident beams. An additional en-face image gives information about the orientation of the vector with respect to the detection plane and allows for measurement of the absolute velocity.
A new method for measurement of absolute flow velocities in glass capillaries as well as in human retinal vessels has been developed and evaluated. The influence of bulk movements was almost completely compensated by our algorithm. Dual-beam bidirectional FD-OCT could serve as a new tool for the study of various ocular diseases and perfusion changes due to physiological or pharmacological stimuli.
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