Optical coherence tomography (OCT) has become an indispensable ophthalmic diagnosis tool due to its fast, noninvasive, three-dimensional features and micrometer resolution. Its functional extension, OCT angiography (OCTA), has recently been translated into the clinic for replacing dye-based fluorescence angiography. However, the performance of currently available commercial OCT/OCTA systems are limited by the field of view, algorithm/system sensitivity, and lack of real-time scan quality evaluation capability. This dissertation presents technical improvements for both OCT systems and OCTA algorithms.