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Optical coherence tomography angiography
Optical coherence tomography angiography (OCTA) is a non-invasive imaging technique based on optical coherence tomography (OCT) developed to visualize vascular networks in the human retina, choroid, skin and various animal models. OCTA may make use of speckle variance optical coherence tomography. OCTA uses motion contrast between cross-sectional OCT scans (B-frames) to differentiate blood flow from static tissue, enabling imaging of vascular anatomy. To correct for patient movement during scanning, bulk tissue changes in the axial direction are eliminated, ensuring that all detected changes are due to red blood cell movement. This form of OCT requires a very high sampling density in order to achieve the resolution needed to detect the tiny capillaries found in the retina. This has allowed OCTA to obtain detailed images of retinal vasculature in the human retina and become widely used clinically to diagnose a variety of eye diseases, such as age related macular degeneration (AMD), diabetic retinopathy (DR), artery and vein occlusions, and glaucoma.