Abstract:

Optical coherence tomography angiography (OCTA) is a new method of analysis based on high-resolution imaging techniques whereby the retinal and choroidal circulation can be visualized without the need to injecting any contrast agent. OCTA operates on the principle that, all other elements remaining the same, the only difference between sequentially obtained OCT cross-sectional scans in a particular eye is attributed to motion of erythrocytes within the retinal and choroidal vasculature. Recently, a new algorithm——split-spectrum amplitude decorrelation angiography (SSADA) has been used in OCTA. It can identify movement orthogonal or transversal to the OCT beam, quantifying flow independent of the Doppler angle. An additional advantage of the amplitude-based technology, in comparison with the phase-based, is that the latter is more significantly degraded by image noise and background tissue motion. OCTA with SSADA has been widely used in various kinds of ocular diseases, such as choroidal neovascularization, diabetic retinopathy and retinal vascular occlusions and it is very important in the diagnosis and follow up in those diseases.  (Int Rev Ophthalmol,  2016,  40:     112-116)