Optical Coherence Tomography vs Optical Coherence Tomography Angiography in the Differential Diagnosis of Choroidal and Vitreoretinal Diseases

Optical coherence tomography (OCT) is a practical and common imaging method for the study of diseases of the retina, choroid, and vitreoretinal interface. Software and technological advances have allowed us to observe changes in the retinal at resolutions less than 5 µm; the development of angiography with OCT (OCTA) allows us to three-dimensionally evaluate the existing perfusion in the analyzed retina and choroid non-invasively and without a specific dye, such as fluorescein or indocyanine green angiography. We can detect important clinical differences between OCT and OCTA, although these approaches are complementary. Diabetic retinopathy, vascular occlusions, and choroidal neo-vascularization secondary to age-related macular degeneration and other causes are among the conditions whose diagnosis, treatment, and follow-up benefit from applying these techniques. Leak quantification in cases of macular edema is a good candidate for future objective evaluation; currently, its existence is only demonstrable in structural OCT, although it can be indirectly inferred in OCTA by observing vascular displacements and deformity of the capillary walls. Using OCTA, it is possible to detect intravascular flow even in fibrous tissue, thereby allowing the evaluation of neo-vascular activity in vasoproliferative diseases. 

Keywords: OCT, OCTA, Segmentation, Macular telangiectasia, Diabetic retinopathy, Macular degeneration, Vascular occlusion, Arterial occlusion, Venous occlusion, Choroidal neo-vascularization, Macular ischemia, Macular edema, Myopic neo-vascularization.