Indocyanine Green (ICG) angiography is useful in detecting abnormalities in the layer of the blood vessels which is just under the retina known as choroid. These blood vessels have an essential role within the eye including providing the retina with oxygen and nutrients. The choroidal vessels related abnormalities are best  diagnosed with the help of ICG angiography imaging.

Similar to fluorescein angiography, ICG dye is injected into a vein within the arm. A camera with certain light filters are used to focus on the choroidal vessel layer. ICG angiography is often performed as a separate test but it is frequently utilized in conjunction with fluorescein angiography to give the retina specialist a more comprehensive picture of the blood vessels in the back of the eye.

When analyzing different retinal diseases, ICG imaging of the choroidal vessels may be beneficial in certain conditions like Age-related degeneration and inflammatory diseases of the choroid and retina.