Fluorescein angiography (FA) involves the use of a special dye and a camera to track the flow of blood through blood vessels in the back of the eye.1
What is fluorescein angiography?
Fluorescein angiography was first safely used in 1961 and has been a staple of eye imaging ever since.1 It helps doctors differentiate between various retinal conditions and also helps them determine whether laser treatment of the retina might be beneficial. FA is often performed as part of a comprehensive dilated eye exam to help diagnose AMD and CNV in myopic macular degeneration.
What happens when you have a fluorescein angiography?
During the test, a contrast substance called sodium fluorescein is injected into a vein in the arm. The contrast then travels very quickly through the bloodstream to reach the eye (and other organs). Approximately 12 seconds after the dye is injected into your arm, it reaches the retina; about 10 minutes after the initial injection, most of it is gone from the eye completely.1 The camera that is used for fundus photography is also used in FA to take pictures of the retina as the contrast goes through the blood vessels. Filters are applied to the camera to highlight the fluorescein dye in the retinal blood vessels.1
Signs of macular degeneration
If there is an eye condition involving the back of the eye and/or the retinal blood vessels, the images may show dye leakage, staining, blocking, or other defects as a result of the abnormality. In particular, leakage of dye from abnormal blood vessels underneath the retina may be one sign of active wet AMD or CNV in myopic macular degeneration.
Risks
Every medical procedure has risks, although the risks of FA are fairly low. After the dye is injected into a vein in your arm, your skin may turn yellow-ish for a while (the dye is yellow); this will fade as your body excretes it. Your urine and sweat may turn an orange-like color; this should resolve within 24 to 48 hours.2 If you have impaired kidney function, it might take a little longer to clear the dye from your system. During the test, you might be slightly nauseous, but this is usually very brief.
Allergic reaction
Rarely, one might develop an allergic reaction to the dye. This can manifest as a rash near the injection site or itching. To treat this, an antihistamine is often given. If you have trouble breathing, this can be a sign of a more severe allergy, and you should alert your doctor and his/her medical staff immediately in order to be treated appropriately.
Appropriate tests and procedures
Talk with your doctor about whether FA is appropriate for your eye condition, and what the risks and benefits are for you. While it is one of the mainstays of eye imaging, it is not the only imaging procedure available, and your doctor can let you know if they want to do FA, or do FA in conjunction with other tests or procedures.