Phase-contrast OCT imaging of transverse flows in the mouse retina and choroid.
OBJECTIVE
To test the hypothesis that a novel phase-contrast optical coherence tomography (OCT) system can image retinal and choroidal vessels in the living mouse.


METHODS
A high-speed spectral domain optical coherence tomography (SDOCT) system, which measures the reflections for the entire depth of the retina at once with each axial scan (A-scan), was developed for mouse retinal imaging. Acquiring multiple A-scans over a transverse line across the mouse retina offers a two-dimensional cross-sectional image (B-scan); several neighboring B-scans can be assembled into a three-dimensional OCT image. To visualize mobility and transverse flow in retinal vessels, the statistical variance of phase for each location was calculated from multiple B-scans acquired successively for the same retinal cross-section. Such measures of phase variance offer a direct measure of motions over a large dynamic range of flow velocities.


RESULTS
Three-dimensional phase-contrast images of the live mouse retina were created using multiple two-dimensional cross-sectional image slices through the retina. For the data presented here, each cross-sectional phase-contrast slice resulted from five images of 100 or 200 transverse pixels, acquired over 25 ms or 50 ms, respectively. The approach offered clear identification of motion regions at different depths, including flow in the retinal microvasculature and in the choroidal vessels.


CONCLUSIONS
Phase-contrast OCT enables three-dimensional visualization of retinal and choroidal vasculature in vivo.
Department of Applied Physics, Division of Biology, California Institute of Technology, Pasadena, California, USA.
Jeff
J
Fingler
Carol
C
Readhead
Daniel M
DM
Schwartz
Scott E
SE
Fraser
D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology*; D002829:Choroid / Q000098:blood supply* / Q000502:physiology; D021621:Imaging, Three-Dimensional / Q000379:methods; D051379:Mice; D015203:Reproducibility of Results; D012160:Retina / Q000033:anatomy & histology* / Q000502:physiology; D012171:Retinal Vessels / Q000033:anatomy & histology* / Q000502:physiology; D041623:Tomography, Optical Coherence / Q000379:methods*