Fluorescein angiography

Fluorescein angiography is a diagnostic procedure. A special camera is used to take a series of photographs of the retina, the light sensitive tissue in the back of the eye.

A special water soluble dye (fluorescein) is injected into a vein in the arm. The dye travels through the veins and into the arteries which circulate throughout the body. (This procedure is often confused with an X-ray angiogram where an iodine dye is injected into a vessel.)

As the dye passes through the blood vessels of the retina, a special camera flashes a blue light into the eye and takes multiple photographs of the retina.

If the blood vessels are abnormal, the dye may leak into the retina or stain the blood vessels. Damage to the lining underneath the retina or the appearance of abnormal new blood vessels growing beneath the retina may also be revealed. The precise location of these abnormalities may be determined by a careful interpretation of the fluorescein angiogram.

Why is a fluorescein angiography done?

Diabetes, the leading cause of blindness in patients under the age of 55, can cause the blood vessels of the retina to leak fluid or blood. In some cases, these abnormalities can be treated with a laser to help prevent loss of vision.

Age-related macular degeneration is the leading cause of blindness in patients over the age of 55. In some cases, small blood vessels can be seen under the retina which can be treated with a laser in an attempt to prevent severe visual loss.

Knowing exactly where a leak is can guide laser treatment with pinpoint accuracy.

What are the risks of fluorescein angiography?

After the fluorescein dye is injected, your skin may turn yellowish for several hours. This colour disappears as the dye is filtered out of the body by the kidneys. Because the dye is removed by the kidneys, your urine will turn dark orange for up to 24 hours following the test.

A few individuals may experience slight nausea during the procedure, but this usually passes within a few seconds. If the dye leakes out of a fragile vein during the injection, localised burning and yellow staining of the skin may occur. This burning usually lasts only a few minutes and the staining will go away in a few days.

Allergic reactions to fluorescein dye are rare. If they occur, they may cause a skin rash and itching. This is usually treated with oral or injectable antihistamines, depending on the severity of the symptoms.

Life threatening allergic reactions (anaphylaxis) are extremely rare. Being allergic to x-ray dyes which contain iodine does not mean that you will be allergic to fluorescein.