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.

OCTA is an effective noninvasive imaging technique that can provide additional information regarding the localization and morphology of vascular lesions in all cases of NV of the optic disc and in more than half of cases of NV elsewhere, suggesting that it is a noninferior technique for the study of posterior pole alterations compared with FFA, which remains the gold standard and is fundamental for the study of the retinal periphery.

OCTA is an effective, non-invasive imaging technique that can offer additional information regarding the morphologies and vascular characteristics of macular lesions in paediatric ophthalmology. Because of the rarity and characteristics of many paediatric macular pathologies, further multi-centric research is required with regard to the utilisation and features of OCTA imaging.

Fellow eyes of Coats patients carry quantitative foveal vascular alterations at SCP. These may represent markers of altered inner blood-retinal barrier, due to a bilateral defect in midcapillary angiogenesis.