Indocyanine green angiography (ICG) is a clinical test used to detect abnormal blood vessels in the choroid, the layer of blood vessels under the retina. These abnormal blood vessels, typically associated with macular degeneration, may cause bleeding, scarring, and vision loss. If the blood vessels can be restricted with treatment, vision loss may be stabilized or improved.
Indocyanine, a harmless green dye, gives off infrared light. When injected into the bloodstream, the dye travels through the veins to the blood vessels in the eye. A video camera connected to a computer picks up the infrared light and makes a picture of the blood’s circulation. No film or X-rays are involved.
Following the test, the liver removes the dye from the body. There is little risk in having an ICG angiogram. Some people may have mild allergic reactions and, although rare, a few severe allergic reactions have been reported in people allergic to iodine, X-ray dyes, and shellfish.
The dye can discolor skin and urine until it is removed from the body by the kidneys. There is little risk in having fluorescein angiography, though some people may have mild allergic reactions to the dye. Severe allergic reactions have been reported but only very rarely. Being allergic to X-ray dyes with iodine does not mean you will be allergic to fluorescein. Occasionally, some of the dye leaks out of the vein at the injection site, causing a slight burning sensation that usually goes away quickly.