Clinical applications of OCT angiography

Background. Optical coherence tomography angiography (OCT-A) allows noninvasive, depth-selective visualization of retinal and choroidal vascular networks by detecting the endoluminal blood flow. This results in three-dimensional high-resolution images which are not possible by regular fluorescein angiography in this spatial resolution. Thus, OCT-A can be used to visualize the microperfusion of retinal and choroidal vessels and their alterations due to diverse pathologies and during the course of therapy. Based on several clinical case reports this article gives an overview of the wide range of applications of OCT-A. Methods. The OCT-A images were obtained with the Spectralis OCT-2 prototype (Heidel-berg Engineering, Heidelberg, Germany). This device provides an increased A scan rate of 70 kHz, which allows the generation of high-resolution OCT volume scans. Results. The areas of application are manifold and include neovascular age-related macular degeneration, diabetic retinopathy, retinal vascular occlusion, inflammatory diseases and telangiectasia of various etiologies. The resulting images and their interpretation differ significantly from regular fluorescein angiography. Knowledge of these differences and of the limitations of this novel diagnostic device are of importance for its clinical application. For certain indications, OCTA may be used as a substitute for invasive fluorescein angiography and provides more de-tailed information, particularly due to the absence of blockage phenomena, such as pooling or staining. Conclusion. The use of OCT-A allows visualization of the microperfusion of the retinal and choroidal vascular networks and their alterations due to diverse diseases in high resolution and with segmentation of different anatomical layers. The exact interpretation of the three-dimensional OCT-A images and their clinical application are currently under clinical evaluation.