Angiography

Angiography is a diagnostic testing procedure in which detailed photographs of the retina and choroid are taken after injecting a dye into an arm vein. The dye circulates through the blood vessels in these tissues and, depending on the condition, certain diagnostic and treatment decisions may be made. Two different dyes are available for injection into the vein: fluorescein or indocyanine green.

The test is performed on an outpatient basis and involves sitting in front of a special camera while flash photographs are taken. Initially, the dye is painlessly injected into an arm vein. When the dye arrives in the eye circulation, the photographs begin. The test usually lasts from 10 to 30 minutes. No X-rays are taken.

Fluorescein dye is removed from the body by the kidneys and ICG dye by the liver. After fluorescein angiography, the urine and skin turn orange for up to 24 hours, after ICG angiography, no color changes in the urine or skin are noticed.

What are the differences between fluorescein and ICG angiography? Fluorescein angiography is the best test to view the retinal circulation while ICG angiography is better to view the choroidal circulation. The infrared light emitted by the ICG can be captured by the camera allowing visualization of the deeper tissues of the eye.

Fluorescein angiography is the most common test performed by the vitreo-retinal specialist. It is useful for diagnosing retinal or optic nerve conditions, guiding laser surgery, and following the course of your condition. Diabetic retinopathy, macular degeneration, retinal vein occlusions, and macular edema are just some of the more common disorders that fluorescein angiography is helpful in assessing.

ICG angiography is most helpful in patients with "wet" macular degeneration. Abnormal blood vessels that grow underneath the retina are sometimes blocked by blood or pigment when imaged with fluorescein. These same blood vessels may be visible with ICG. If they are precisely located, laser surgery may be offered. ICG is also useful in evaluating ocular tumors and inflammatory conditions.

Side effects of the procedure include nausea and a yellow staining of the skin at the site of the injection. Nausea, when it occurs, usually passes within a few seconds. Staining of the skin may occur if the fluorescein dye leaks out of a fragile vein, and may also be accompanied by localized burning. The burning usually lasts only a few minutes, and the staining will go away after a few days. Allergic reactions to fluorescein dye are uncommon. If allergies do occur, they may manifest as a skin rash or itching. Depending on the severity of the allergic reaction, the treatment may take the form of an oral or injectable antihistamine. Rarer still, are severe allergic reactions or anaphylaxis, which, if they do occur have the potential to be life threatening.

ICG dye contains iodine. Severe allergic reactions may occur when ICG is injected into those people who are allergic to iodine. If you suspect that you are allergic to substances that contain iodine, including X-ray dyes and shellfish, you must alert you physician.

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