Swept-Source Optical Coherence Tomography Angio™ (Topcon Corp, Japan): Technology Review

Optical coherence tomography (OCT) angiography (OCTA) is a novel, noninvasive, three-dimensional imaging technique that allows for the visualization of intravascular flow in the microvasculature. Swept-source OCT technology utilizes longer-wavelength infrared light than conventional spectral-domain OCT. This enables improved penetration into tissue and imaging through optical opacities and is invisible to the subject. Topcon has recently developed an innovative OCTA algorithm, OCTARA (OCTA Ratio Analysis), which benefits from being paired with swept-source OCT. OCTARA aims to provide improved detection sensitivity of low blood flow and reduced motion artifacts without compromising axial resolution. In this chapter, we describe the implementation of OCTARA with swept-source OCT technology, the technical specifications of acquisition (e.g. the number of scans, area of examination field, etc.) along with the algorithm's function and principles for analysis of B-scan data to achieve angiographic visualization. Examples of OCTA scans performed using the OCTARA algorithm and a comparison of these scans with images obtained using other technologies are also presented.