Optical coherence tomography (OCT) is a new diagnostic technology for high resolution, cross-sectional, quantitative imaging of the human retina. OCT is a noninvasive, noncontact technique which uses near infra-red, lowcoherent light passing through a Michaelson interferometer. OCT is essentially analogous to ultrasound B-mode imaging except that optical rather than acoustic reflectivity is measured. OCT is unique, amidst other current technologies, in its cross-sectional scanning of the tissue which provides anatomic tomographic representation of the retinal layers and their pathologies, and in its exceptionally high resolution (approximately 10 μm) and reproducibility. OCT provides powerful diagnostic information which is complementary to conventional studies such as fundus photography and fluorescein angiography, and is extremely useful in the diagnosis and monitoring of retinal disorders such as macular hole and macular edema of various origins, and for nerve fiber layer thickness measurement in glaucoma. In addition, OCT has the potential for a wide variety of corneal and anterior segment imaging.