Ophthalmic Application of Optical Coherence Tomography Based Angiography for Choroidal Imaging

Abstract

We demonstrated in vivo choriocapillaris imaging in normal human subjects with a Cirrus HD 5000 spectral domain OCT prototype. With the tracking system installed in the prototype and the montage scanning protocol, wide field OCT angiograms of 9 mm * 11 mm were created. OCT angiography utilizes the intrinsic motion of red blood cells as contrast mechanism therefore requires no exogenous contrast agents as fluorescein angiography and indocyanine green angiography do. Four consecutive OCT scans were acquired at the same location for angiography generating, intensity based, phase based and complex signal based OCTA were all computed and compared. With the ability to resolve fine and detailed vascular lobules, complex signal based OMAG were selected for en face visualization. In consistency with histological studies, lobular vascular networks were observed and corresponding feeding arterioles were identified in OMAG images. Structural OCT en face image was also generated and at periphery regions, lobular structures can also be recognized with distinct brightness patterns. This study showcased the feasibility of using commercialized SD-OCT for in vivo choriocapillaris visualization and essentially opens the possibility for clinical imaging studies on choriocapillaris’ role in pathogenesis and early diagnosis of ocular disease.