OCT angiography and evaluation of the choroid and choroidal vascular disorders

The recent introduction of optical coherence tomography angiography (OCTA) has remarkably expanded our knowledge of the choroid through in vivo investigation of the anatomical and pathological features of this important vascular layer. New insights elucidating the morphological features of the choroid, in both physiological and pathological conditions, indicate that this vascular structure plays a crucial role in many chorioretinal disorders. In this article, a review of the salient histological and anatomical features of the choroid, essential for the proper interpretation of in vivo imaging, is followed by a discussion of the fundamental principles of OCTA and the application of this advanced imaging modality to study and understand the choroid. The current limitations of OCTA and potential advancements that may improve the widespread adoption of this tool are also discussed. A detailed review of the OCTA features of the choroid in the healthy eye is followed by relevant findings in major chorioretinal diseases, including age-related macular degeneration, central serous chorioretinopathy, uveitis, and inherited retinal disorders.