Variable velocity range imaging of the choroid with dual-beam optical coherence angiography

In this study, we present dual-beam Doppler optical coherence angiography with variable beam separation. Altering beam distance, independently of the scanning protocol, provides a flexible way to select the velocity range of detectable blood flow. This system utilized a one-micrometer wavelength light source to visualize deep into the posterior eye, i.e., the choroid. Two-dimensional choroidal vasculature maps of a human subject acquired with different beam separations, and hence with several velocity ranges, are presented. Combining these maps yields a semi-quantitative visualization of axial velocity of the choroidal circulation. The proposed technique may be useful for identifying choroidal abnormalities that occur in pathological conditions of the eye. (C) 2011 Optical Society of America