Optical coherence tomography (OCT) is an imaging technology that can perform non-contact cross-sectional imaging of retinal and choroidal tissue structure in real time by measuring the intensity of reflected light. Tomographic images are generated by scanning the optical probe beam across the tissue structure of interest. OCT has become one of the most widely used imaging technologies by ophthalmologists. Its advantages include being a non-contact imaging modality, having micron-level resolution, producing a digital image that can be viewed electronically, and providing a reproducible quantitative measurement. New functional OCT including Doppler OCT and OCT angiography may allow an assessment of retinal blood flow and do away with the need for the more invasive fluorescein angiography (FA) test.