Introduction to swept source optical coherence tomography angiography

Swept source optical coherence tomography (OCT) technology and OCT-angiography (OCT-A) are two recent developments that have the potential to significantly change our understanding of retinal pathology and retinal vascular pathophysiology. In order to correctly use these technologies to their full diagnostic potential, a thorough understanding of the technology as well as its benefits and limitations is essential. The aim of this review article is to provide an introductory understanding of how swept source OCT with a 1050 nm wavelength differs from conventional spectral domain OCT using 840 nm wavelength, and what the benefits are. The OCTARA™ swept source OCT angiography algorithm will be explained and compared with other algorithms. The cause and removal of projection artifacts, white band artifacts, black band artifacts, speckle noise and flicker noise in swept source OCT-angiography (OCT-A) will be explained. Layer segmentation boundaries and the reasons for them will be explained. The benefit of wide-field OCT-A will be discussed using case examples. Finally, the challenges of OCT choroidal angiography will be discussed.