Fluorescein angiography can be referred to as “F.A.” or “the dye test.” During the test, we use a dye called fluorescein. Only about a teaspoon of the dye is used and it is injected into a vein in the arm using a very small needle of a size that is typically used in children. After the dye is injected, it travels through the bloodstream to the blood vessels in the eye, which are photographed with a camera. The dye highlights abnormalities in the blood vessels by “leaking” in a specific pattern that is recorded by the camera. This leakage can be used to detect disease abnormalities long before they can be detected by a general eye doctor’s examination, and before the patient can detect anything wrong with their vision. Fluorescein angiography is the gold standard in detecting abnormalities of the retinal blood vessels and is the most sensitive test available in medicine for this purpose. The test takes only about six minutes to perform.
Fluorescein is a very mild dye that does not harm the kidneys. It also does not contain any iodine that would give an allergic reaction like other dyes used in medical tests can. The most common reaction to the fluorescein dye is a very brief feeling of nausea that lasts a few seconds and goes away. The skin may also turn little yellowish but this goes away in a few hours. Finally, the dye can cause one’s urine to be a little darker than usual for a day or so. Very rarely, some patients may feel a brief itching sensation or a brief rash after the dye is injected. In these situations we give Benadryl for the patient to take to prevent any significant allergic reaction from developing further. Any reactions to the fluorescein that might occur will happen within a few minutes after it is injected into the vein. Any symptoms that start over an hour after the test is performed are almost certainly not due to the dye test, and are likely caused by something else. Although theoretically any serious side effect is possible, in our nearly two decades of practice, after having performed tens of thousands of dye tests over many years, no patient has ever developed any serious reactions to the dye test.
Occasionally, an additional dye called indocyanine green (or "ICG" for short) is used in combination with fluorescein.