There is increasing interest in new imaging techniques for the assessment of funcional parameters in the eye.
Among other parameters measurement of retinal blood flow is of particular interest, because a number of high-
incidence ocular diseases such as diabetic retinopathy, retinal vein occlusions and glaucoma include a vascular
component.
We have recently introduced a new method to assess retinal blood flow in arterioles and venules in vivo. With this
technique, called Fourier Domain Optical Coherence Tomography, the principals of Optical Coherence
Tomography and Laser Doppler Velocimetry are combined. Realization of a prototype instrument was made
possible by a grant from the Austrian FWF and we could show that flow velocities in retinal vessels can be
assessed with high transversal and logitudinal resolution. The overall goal of the present grant proposal is to
translate this technique into clinical application. Specifically three aims are anticipated:
1. The present prototype system does not allow for measurement of absolute velocities in retinal vessels.
Accordingly, a bi-directional Fourier Domain Optical Coherence Tomograph will be set up, allowing for absolute
measurement of blood velocities in retinal arteries and veins.
2. Validation of the system by comparison with existing technology and assessment of reproducibility and
sensitivity. This will be done in healthy subjects by using 100% oxygen breathing as a stimulus to reduce retinal
blood flow.
3. Application of the technique in patients with retinal vein occlusions and diabetic retinopathy. In patients with
retinal vein occlusion the system may have considerable potential in quantifying retinal ischemia and may therefore
help in guiding therapeutic decisions. In patients with diabetic retinopathy a main goal is to estimate shear stress on
the vascular endothelium based on the measured velcoity profiles in retinal vessels.