Indocyanine green angiography (ICGA) is an important imaging modality for the diagnosis and management of uveitis. Indocyanine green (ICG) is a water-soluble, tricarbocyanine dye. Being completely protein-bound (98%) after intravenous injection, it has limited diffusion through the small fenestrations of the choriocapillaris. Thus, due to its low permeability, the ICG dye retains in the choroidal circulation and is ideal for imaging choroidal circulation. ICG fluoresces in the near-infrared range (790–805 nm). Specialized infrared fundus cameras with digital imaging system are required to perform ICGA. Due to its longer operating wavelength, ICG fluoresces better through pigment, fluid, lipid, and hemorrhage than fluorescein dye. This property of ICG is useful in detecting pathologies such as CNV that may be blocked by an overlying hemorrhage or hyperplastic RPE on a fluorescein angiogram. Though a relatively safe procedure, it may have mild adverse reactions including nausea, vomiting, sneezing (0.15%), urticaria (2%), and severe adverse reactions such as decreased blood pressure, anaphylaxis (0.05%). Despite being less popular than fluorescein angiography, ICGA plays an important role in diagnosis and management of choroidal pathologies.
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