Optical coherence tomography (OCT) (Stratus OCT, Carl Zeiss Meditec, Inc., Dublin, CA) (Fig. 10.1) is a commercially available computer-assisted precision optical instrument that generates cross-sectional images (tomograms) of ocular structures with close to 10-μm axial resolution.1 This technology is evolving, and its axial resolution has been reported to be as high as 3 μm in laboratory settings (ultrahigh-resolution OCT).23 Optical coherence tomography is analogous to B-mode ultrasound, except that it uses light rather than sound. Unlike ultrasound, OCT does not require contact with the tissue examined. © 2009 Springer New York.