The camera takes a series of photographs as the dye passes through the blood vessels at the back of the eye. No X-rays are involved. The entire procedure usually takes less than 30 minutes. Because fluorescein dye is removed from the body by the kidneys, the urine turns orange for up to 24 hours. In addition, the skin can turn slightly yellow for several hours.
ICG dye is removed from the body by the liver, and no color changes are noticed.
Most angiograms are done with fluorescein. The most common reason to do an ICG angiogram is to detect abnormal choroidal blood vessels beneath the retina in people with macular degeneration. Abnormal blood vessels can damage vision by bleeding and scarring. An ICG angiogram can sometimes locate abnormal choroidal vessels better than a fluorescein angiogram. Although they are not known to cause birth defects, fluorescein and ICG should be used with caution in pregnant women.