Three-Dimensional Angiography of Classic and Occult Lesion Types in Choroidal Neovascularization

To identify characteristic features of classic and occult choroidal neovascularization (CNV) by using a novel technique of topographic angiography for three-dimensional (3D) visualization. A confocal scanning laser ophthalmoscope (SLO, Heidelberg Retina Angiograph; Heidelberg Engineering, Dossenheim, Germany) was used to perform fluorescein (FA) and indocyanine green (ICGA) angiography in158 patients. Ninety-four eyes had predominantly classic and 64 eyes had occult lesions. With an image frequency of 20 Hz, a tomographic series of 32 images per set were taken over a depth of 4 mm. Axial analyses for each x/year position were performed, to determine the fluorescence distribution along the z-axis. After the axial location of hyperfluorescence was detected, a depth profile was generated. All results were integrated into a gray-scale-coded depth image and imaged as a 3D relief. Characteristic features of classic and occult lesions were distinguished. Classic CNV appeared as a well-demarcated lesion with steep, prominent borders, often craterlike, and frequently surrounded by a halo, suggesting choroidal perfusion changes. Occult CNV was documented by 3D as a convex lesion with flat, ill-defined borders and without any surrounding halo. Topographic imaging is superior to conventional angiography regarding definition of lesion type, configuration, and extension, because masking phenomena do not interfere. Topographic angiography allows a realistic 3D representation of CNV. Characteristic features based on the neovascular architecture and the differences in leakage behavior of different lesion types are clearly identified.