Abstract
Purpose :
Motion within the retina can be measured with high sensitivity by evaluating the phases of optical coherence tomography (OCT) signals. OCT angiography and Doppler OCT use this principle to visualize vessels and measure blood flow. Also, local retinal deformation driven by blood pulsation was determined from the phase with nanometer resolution. However, the OCT signal provides only information on motion along the direction of the light propagation, motion in the two orthogonal directions cannot be measured directly. Motion direction or its absolute value are not known without additional assumptions. We demonstrate a new approach for a quantitative determination of all three components of the motion vector using OCT volumes with stable phase relation.
Methods :
Motion within the retina can be measured with high sensitivity by evaluating the phases of optical coherence tomography (OCT) signals. OCT angiography and Doppler OCT use this principle to visualize vessels and measure blood flow. Also, local retinal deformation driven by blood pulsation was determined from the phase with nanometer resolution. However, the OCT signal provides only information on motion along the direction of the light propagation, motion in the two orthogonal directions cannot be measured directly. Motion direction or its absolute value are not known without additional assumptions. We demonstrate a new approach for a quantitative determination of all three components of the motion vector using OCT volumes with stable phase relation.
Results :
Test in phantoms and excised porcine eyes demonstrated an accuracy in the nanometer range for the two lateral motion components. Crucial was an exact numerical refocussing onto the plane of interest. At typical retinal imaging conditions, even a small defocus may introduce an artefact that is larger than the actual lateral motion. In vivo measurements were successfully demonstrated with volunteers.
Conclusions :
Acquiring phase-stable OCT volumes of the retina enables 3-D motion measurements with high accuracy. Possible applications are quantitative blood flow measurements, elastography of the retina and the measurement of local temperature increase and tissue denaturation during retinal laser treatment.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.