Role of indocyanine green fluorescence videoangiography in evaluation of subretinal disease

BACKGROUND: Indocyanine green (ICG) is a sterile, water-soluble, tricarbocyanine dye that can be used in fundus angiography as an adjunct to sodium fluorescein. It has a peak spectral absorption of 805 nm in blood plasma or blood, as compared with fluorescein, which has a peak spectral absorption of 465 nm. Because the absorption and emission of ICG lies around 835 nm, transmission of energy by the retinal pigment epithelium (RPE) and serosanguinated material is more efficient in this region than in the region of visible light energy. ICG has the property of being approximately 98% bound to blood protein, disallowing extravasation of excessive dye in the highly fenestrated choroidal vasculature. METHODS: The characteristics of ICG are discussed, including administration and dosage, adverse reactions and use of infrared filters for fundus photography. In addition, two cases are presented to illustrate the clinical application of ICG for diagnosis and treatment of choroidal neovascular membranes. RESULTS: ICG videoangiography can be used to reveal subfoveal choroidal neovascular membranes not previously identified with fluorescein; angiograms can also be used to dramatically highlight retinal and choroidal changes. CONCLUSIONS: The use of ICG for fundus videoangiography provides a more accurate and complete evaluation in certain cases of subretinal and choroidal disease.