A Prototype Instrument for Simultaneous Indocyanine Green (ICG) Angiography and Multi–planar Optical Coherence Tomography(OCT) Imaging of the Retina

Purpose: To describe preliminary results using a prototype instrument which can simultaneously acquire multi–planar OCT images and ICG angiographic studies of the fundus. Methods:The instrument employs a scanning interferometer configuration which produces paired C–scan planar OCT and confocal ophthalmoscopic images. The optical source, a superluminescent diode (SLD)?= 793 nm, is used for both OCT reflectometry and for the excitation of the ICG fluorescence. The system is also capable of providing OCT B–scans at selected points from the ICG confocal image. Subjects were studied pre and post injection of ICG dye into an antecubital vein. Special care was given to capture early transit phase images through the choroid and retina and corresponding late phase images for evidence of delayed fluorescence accumulations. OCT B–scan sequences were collected in response to observed areas of increased fluorescence seen in the confocal channel. Results:Images from 5 healthy eyes and 5 eyes with macular degeneration have been initially obtained. The vasculature is well defined in the confocal ICG image, while patchy and difficult to trace in the OCT image. At the same time, the depth resolution in the ICG channel is low (?1 mm) and anatomic relationships are flattened. The overlay feature of the viewing software allowed the precisely registered images to fuse, permitting accurate localization of fluorescence highlighted features in depth. Conclusions:The multi–planar C–scan OCT/ICG ophthalmoscope provides a unique integration of OCT morphologic and ICG angiographic functional imaging technologies. The pixel–to–pixel correspondence inherent in of this system allows accurate superimposition of the paired image channels which may better help elucidate some of the complex relationships between the 3–dimensional anatomy and the retinal and choroidal circulations.