Indocyanine green angiography (ICG) is a similar procedure to fluorescein angiography. It however involves a different diagnostic dye that circulates through the deeper ocular circulation and allows the choroidal layer of the eye to be imaged. ICG angiography is often used in conjunction with fluorescein angiography and is particularly useful for patients with polypoidal choroidopathy (a variant of macular degeneration).
Photographs of the retina and the blood vessels are taken as the dye circulates through the blood stream. This test allows a detailed evaluation of any blockage, leakage of dye, or areas of ischaemia (poor circulation) in the choroid and is important for the doctors to diagnose or monitor your eye condition.
The procedure usually takes about half an hour to complete. The retina is photographed with a specialized digital camera as the dye travels through the choroidal and retinal circulation. Bright flashes of light from the camera will be experienced. After having an ICG angiogram, we advise that you are accompanied by a family member or friend and that you do not drive home yourself after the appointment.
The risks associated with injection of ICG are low and most patients do not experience any significant side effects. In rare cases, ICG can cause nausea and allergic reactions. As ICG dye contains iodine, this procedure is contraindicated in individuals with an allergy to iodine, shellfish, certain cough mixture, betadine or other iodine contrast agents.