Feature Of The Week 7/6/2015: Ultra-Widefield Retinal MHz-OCT Imaging With up to 100 Degrees Viewing Angle
We evaluate strategies to maximize the field of view (FOV) of in vivo retinal OCT imaging of human eyes and analyze the problems caused by the increased scan angle. Three imaging modes are tested: Single volume imaging with 85° FOV as well as with 100° and stitching of five 60° images to a 100° mosaic (measured as usually from the nodal point). We employ a MHz-OCT system based on a 1060nm Fourier domain mode locked (FDML) laser with a depth scan rate of 1.68MHz. The high speed is essential for dense isotropic sampling of the large areas. Challenges caused by the wide FOV are discussed and solutions to most issues are presented. Detailed information on the design and characterization of our sample arm optics is given. We investigate the origin of an angle dependent signal fall-off which we observe towards larger imaging angles. It is present in our 85° and 100° single volume images, but not in the mosaic. Our results suggest that high quality 100° FOV OCT is possible with current swept source OCT technology.
For more information see recent Articles. Courtesy Jan Philip Kolb from University of Lübeck.