Fluorescein Angiography: What to Expect
Understanding Fluorescein Angiography
Fluorescein angiography, often called FA, is a test that uses a yellow dye called sodium fluorescein and a specialized camera to photograph the blood vessels inside your eye. The dye travels through your bloodstream and highlights the vessels in the retina. The retina is the light-sensitive tissue lining the back of the eye. A retina specialist uses these images to look for damaged, leaking, or abnormal blood vessels.
The technique was first developed by two medical students, Harold Novotny and David Alvis, at Indiana University. It was presented to the medical community in the early 1960s. Since then, it has become one of the most widely used diagnostic tools in retinal care. Traditional fluorescein angiography accounted for the largest share of the retinal imaging market at 56.4% in 2024 (Grand View Research, 2024).
Fluorescein angiography works through a physical process called fluorescence. Blue light at a wavelength of 465 to 490 nanometers shines on the fluorescein dye in your blood vessels. The dye absorbs that light and emits a yellow-green glow at a wavelength of 520 to 530 nanometers. The camera uses special filters that block the blue light and capture only the yellow-green glow. This creates high-contrast images of the blood flow in your eye.
After the dye is injected into a vein in your arm, it typically reaches the blood vessels of the eye within about 10 to 15 seconds. The dye first appears in the choroidal circulation, usually within 8 to 12 seconds. It reaches the retinal blood vessels 1 to 3 seconds later. The exact timing depends on your age, heart health, and how quickly the dye is injected.
Fluorescein angiography provides information that other tests may not reveal on their own. It can show tiny leaks in blood vessels, areas where blood flow is blocked, and new abnormal blood vessels growing in the retina. These findings are essential for diagnosing conditions and planning treatment. Treatment may include anti-VEGF injections (medications that block abnormal blood vessel growth), laser therapy, or other interventions.
Conditions Evaluated With Fluorescein Angiography
Age-related macular degeneration, or AMD, is one of the most common reasons a retina specialist orders fluorescein angiography. AMD affects the macula, the central part of the retina responsible for sharp, detailed vision. The test is especially useful for detecting wet AMD. Wet AMD involves abnormal blood vessels that grow beneath the retina and leak fluid or blood.
AMD held the dominant position among fluorescein angiography applications, accounting for the largest revenue share at 32.6% in 2024 (Grand View Research, 2024). The images help a retina specialist determine the type, location, and extent of the disease. These details guide treatment decisions.
Diabetic retinopathy is a complication of diabetes that damages the small blood vessels in the retina. Fluorescein angiography can reveal areas of blood vessel leakage, blocked blood flow, and the growth of new abnormal vessels. These findings help a retina specialist determine the stage of the disease. They also guide decisions about whether anti-VEGF injections or laser therapy is necessary.
A retinal vein occlusion occurs when a vein that carries blood away from the retina becomes blocked. This blockage can cause swelling, bleeding, and vision loss. Fluorescein angiography shows where the blockage is located and how much of the retina is affected. This provides critical information for managing the condition.
Fluorescein angiography is also used to evaluate many other conditions. These include:
- Macular edema, which is swelling in the central part of the retina that distorts vision
- Uveitis, which is inflammation inside the eye
- Retinal tumors or growths
- Central serous chorioretinopathy, a condition where fluid collects under the retina
- Vascular abnormalities or malformations in the retina
Before the Test
Before fluorescein angiography, let your retina specialist know about any allergies you have. This is especially important if you have ever had a reaction to fluorescein dye. If you are also having indocyanine green angiography, also called ICG angiography, inform your specialist about any allergy to iodine or shellfish. The ICG dye contains iodine.
Tell your retina specialist if you are pregnant or think you might be pregnant. Pregnancy is considered a relative reason to avoid the test. However, it may be performed safely in certain situations when the information it provides is essential. Also share any history of heart conditions, kidney problems, or other significant health concerns.
Plan to have someone drive you home, as your pupils will be dilated and your vision may be temporarily blurry after the test. Wear comfortable clothing, as the dye is injected through a vein in your arm, typically near the inside of your elbow. Sunglasses are helpful for the ride home because dilated pupils make your eyes more sensitive to light.
During the Procedure
The entire procedure typically takes a short time and is performed in an office setting. Your retina specialist or a trained technician will guide you through each step.
- Eye drops are placed in your eyes to dilate, or widen, your pupils
- You sit in front of a specialized camera, and baseline photographs of your retina are taken before any dye is injected
- A small amount of sodium fluorescein dye, usually about 5 milliliters, is injected into a vein in your arm
- As the dye circulates to the blood vessels in your eye, the camera takes a rapid series of photographs over several minutes
- Later images may be taken 5 to 10 minutes after the injection to capture how the dye drains from the retinal vessels
The injection itself feels similar to a routine blood draw. You may feel a brief sting or pressure when the needle enters the vein. Some people notice a warm sensation as the dye enters the bloodstream. During the photograph phase, bright flashes of light from the camera are normal. These flashes may cause your vision to appear dark or tinted for a few minutes afterward. This effect is temporary and fades quickly.
After the Test
After fluorescein angiography, the dye temporarily changes the color of your skin and urine. Your skin may appear slightly yellow for a few hours as the dye circulates through your body. Your urine will likely look orange or dark yellow for up to 24 hours after the test. These changes are harmless and go away on their own as your body clears the dye through your kidneys.
Some people also experience mild nausea during or shortly after the injection. This usually passes within a few minutes. Drinking plenty of water after the test can help your body flush the dye more quickly.
Serious reactions to fluorescein dye are uncommon but can occur. In a large national survey of hundreds of thousands fluorescein angiograms, moderate adverse reactions occurred in about 1 in 63 procedures, severe reactions occurred in about 1 in thousands procedures, and death occurred in approximately 1 in hundreds of thousands procedures (Yannuzzi et al., Ophthalmology, 1986). Possible reactions include:
- Hives or itchy skin
- Swelling at the injection site
- Breathing difficulties, which are very rare
- Vasovagal reactions such as fainting or a drop in heart rate
Your retina specialist and clinical staff are trained to manage these reactions if they occur. Emergency medications and equipment are available in the office during the procedure.
Understanding Your Results
In a normal fluorescein angiogram, the dye fills the retinal arteries and veins in an even, predictable pattern. It then drains away without pooling or leaking. The blood vessels appear well-defined, and there are no areas of unusual brightness or darkness. Normal results suggest that the retinal blood supply is healthy and functioning properly.
Abnormal findings can take several forms. Leakage of dye from blood vessels may indicate inflammation, swelling, or wet AMD. Dark areas where the dye does not reach may suggest blocked blood flow. This can occur in diabetic retinopathy or retinal vein occlusion. Bright areas of new dye collection may point to the growth of abnormal new blood vessels, a process called neovascularization.
Your retina specialist will review the images and explain what the findings mean for your specific situation. The results often guide decisions about whether treatment is needed, what type is most appropriate, and how urgently it should begin.
Advances in Retinal Angiography
Standard fluorescein angiography captures images of the central retina. Ultra-widefield fluorescein angiography, or UWFFA, uses advanced camera technology to photograph a much larger area of the retina. This includes the far peripheral regions. Research has shown that UWFFA can detect disease in the peripheral retina that standard imaging may miss. It has led to changes in diagnosis and treatment approaches for some patients.
Oral fluorescein angiography is an alternative approach where the dye is swallowed rather than injected into a vein. This method has a lower risk of allergic reactions. In a study of 1,019 patients who underwent oral fluorescein angiography, no allergic reactions were recorded (Sadiq et al., Retina, 2013). Mild gastric discomfort occurred in less than 1% of patients in that same study (Sadiq et al., Retina, 2013). This approach may be considered for patients who have difficulty with intravenous access or who are at higher risk for injection-related reactions.
Optical coherence tomography angiography, or OCTA, is a newer imaging technology that visualizes retinal blood flow without any dye injection. It creates detailed, three-dimensional maps of the blood vessels in different layers of the retina. While OCTA offers the advantage of being completely noninvasive, it does not provide the same information about dye leakage that fluorescein angiography does. Many retina specialists use both tests together to get a comprehensive picture of retinal health.
When to See a Retina Specialist
If you have a known retinal condition such as diabetic retinopathy, AMD, or retinal vein occlusion, your retina specialist may recommend fluorescein angiography at regular intervals. Following your recommended schedule helps detect progression early, when treatment may be most effective.
Contact a retina specialist promptly if you notice changes in your vision. These include blurred central vision, distortion of straight lines, dark spots in your visual field, or difficulty seeing in low light. These may indicate that your condition is progressing or that a new problem has developed.
Certain symptoms require immediate attention. See a retina specialist or go to the emergency room immediately if you experience a sudden increase in floaters, new flashes of light, a curtain or shadow spreading across your vision, or sudden vision loss in one eye. These could be signs of a retinal tear, retinal detachment, or other sight-threatening emergency.
Questions and Answers
Fluorescein angiography is considered safe for people with diabetes. It is one of the most important tools for evaluating diabetic retinopathy. The dye itself does not interact with insulin or diabetes medications. However, patients with diabetes may have other health conditions such as kidney disease that could affect how the body processes the dye. Your retina specialist will take your overall health into account when recommending the test.
Optical coherence tomography, or OCT, creates cross-sectional images of the retinal layers. It shows their thickness and structure. Fluorescein angiography shows how blood flows through the retinal vessels and whether any vessels are leaking or blocked. OCT is noninvasive and requires no dye. The two tests provide different but complementary information. A retina specialist may order both to get a complete view of your condition.
The frequency depends on your specific diagnosis and how your condition responds to treatment. Some patients need the test only once to establish a diagnosis. Others may have it repeated every few months or annually to monitor changes. Your retina specialist will recommend a schedule based on your individual needs. Alternatives such as OCTA may be considered when appropriate.
Most retina specialists do not require you to fast before fluorescein angiography. Eating a light meal beforehand may actually help reduce the mild nausea that some patients experience after the dye injection. It is best to follow any specific instructions your specialist provides. Recommendations may vary depending on your health history.
If you have a mild allergic reaction such as hives or itchy skin, it can typically be managed with antihistamine medication. More serious reactions, though very rare, are treated immediately with appropriate emergency medications. If you have had a previous reaction to fluorescein dye, inform your retina specialist before the test. In some cases, pretreatment with antihistamines or corticosteroids may be recommended. An alternative imaging method such as OCTA may be used instead.