Evaluation of Confocal Laser Scanning Indocyanine Green Angiography Images of Occult Choroidal Neovascularization

ABSTRACT

For the interpretation of the confocal laser scanning indocyanine green angiography(Heidelberg Retina Angiograph, HRA) in patients with choroidal neovascularization(CNV) secondary to age-related macular degeneration(AMD), we analyzed the early and the late phase images comparatively. HRA was carried out in 41 eyes of 36 patients that revealed occult CNV or undetectable CNV on fluorescein angiograms. In all patients, the image qualitites of HRA was excellent in the early as well as in the late phase studies and CNV was detected in 38 eyes(93%). In 25 eyes(66%), we could get all the possible information of CNV with the early phase images which revealed CNV as fine neovascular networks or vascular structures of lnear or dot pattern usually surrounded by hypofluorescent margins. And when the hypofluorescent margin surrounded the neovascular structure completely, a well-defined CNV could be diagnosed. In 9 eyes(24%), more accurate evaluation of the nature, size and geometry of CNV could be made with the help of more late phase images. In these cases, as the initially identified neovascular structures were stained in the late phase, more intensely leaking portions or more widespread minimally stained areas could be detected. In remaining 4 eyes(10%), CNV could b detected in the late phase without apparent evidence of vascular structure in the early phase. Our study suggests that careful reading of the whole sequence of ICG angiograms and comparative analysis of the early and late phase images are required to get the clinically useful information from HRA.