Intravenous and indocyanine green angiography

Abstract

Indocyanine green angiography (ICGA) is an adjunct procedure to intravenous sodium fluorescein angiography (IVFA) for evaluation of disorders of the retina. It has particular application when choroidal pathology is implicated or suspected. Indocyanine green (ICG) dye has been used in the medical field since 1956, when it was approved by the Federal Drug Administration for imaging cardiac and hepatic circulations. Indocyanine green is a well-tolerated, tricarbocyanine dye with a molecular weight of 775 daltons that absorbs light at 790 to 805 nm and has a peak emission at 835 nm. While the substance gives off 4% the fluorescence of sodium fluorescein, its spectral properties allow it to be visualized through ocular pigments, blood, and serous fluids. Using search engines and library resources, clinically relevant ICGA studies were reviewed for their purpose, description, outcome, clinical importance, and compared and contrasted to IVFA. Information is presented that represents the current modalities of ICGA. ICGA still remains an adjunct therapy to traditional IVFA. However, as the technology improves--allowing easier recording and visualization of ICG angiograms--and as more studies are conducted on the best use of the information obtained from ICGA, this technique may emerge as an important diagnostic tool in the fight to prevent the severe vision loss associated with the various retinal disorders mentioned.