Indocyanine Green Angiography - Carver College of Medicine

ICG is used to acquire an angiogram of the choroid. The choroid is the layer of blood vessels and connective tissue between the sclera (white of the eye) and retina. It supplies nutrients to the inner parts of the eye.

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A procedure similar to fluorescein angiography, but ICG angiography uses Indocyanine Green dye, which fluoresces in the infra-red (non-visible) light. The infra-red wavelenths have the ability to penetrate the retinal layers making the circulation in deeper layers visible when photographed with an infra-red sensitive camera.

ICG is injected intravenously and flows through the body to reach the choroidal and retinal circulation. Due to its nature ICG stays in the retinal and choroidal vessels, this allows the distinct outlines of the vessels of the choroid to be seen and identified. ICG is sometimes used to complement fluorescein angiography (FA). FA is often referred to retinal angiography while ICG angiography is referred to choroidal angiography.

ICG was first used in [1] but was not brought into the practical clinical setting until .[2]

Case Example:

In the case of a patient with 20/100 vision, the fluorescein angiogram demonstrated leakage of fluorescein dye over a large area near the fovea. Traditional treatment would dictate that the entire area of leakage be treated with laser surgery. The treatment of this lesion would cause an instant decline in vision to 20/400.

The ICG angiography, performed on the same day, reveals a pinpoint leak not visible with fluorescein angiography. Focal treatment based on the ICG angiogram caused an increase in vision from 20/100 to 20/80.

After treatment the laser scar is visible on the color fundus photograph. Both the fluorescein and the ICG angiograms show no leakage of dye demonstrating that the focal treatment was effective.

If you want to learn more, please visit our website Retinal Camera.

Photographs by UIHC Opthalmic Imaging Staff

References:

1. Kogure K, Choromokos E. Infrared absorption angiography. J Appl Physiol. ;26(1):154-7.
2. Yannuzzi LA, Slakter JS, Sorenson JA, Guyer DR, Orlock DA. Digital indocyanine green videoangiography and choroidal neovascularization. Retina.;12(3):191-223.

Indocyanine green angiography (ICGA) is a diagnostic test that involves taking photographs of the blood vessels in the eye with the help of a contrast dye. Indocyanine is a green dye that works with infrared light and is visualized with a special digital camera.

These images can help evaluate or detect serious eye conditions such as:

During these exams, the patient&#;s pupils are dilated with eye drops. The contrast dye is then injected, usually into a vein in the patient&#;s arm. The dye travels to the eye within a few seconds and highlights the blood vessels for the camera. Once the dye is injected, multiple photographs are taken over several minutes.

These tests are considered safe for the vast majority of patients. It is possible to have a mild reaction to the dye and develop symptoms including itching, nausea, or a rash. More serious reactions are uncommon.

Patients with an iodine or shellfish allergy should inform the doctor since indocyanine green is contraindicated in these cases.