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Fluorescein Angiography

An imaging test using injected dye to evaluate blood flow in the retina and detect leakage or abnormal vessels.

4 min read

Fluorescein angiography (FA) is an imaging test where fluorescent dye is injected into a vein, and photographs are taken as the dye travels through the blood vessels in the eye. It reveals blood flow patterns, leakage, and vascular abnormalities.

Fluorescein angiography infographic showing dye injection, retinal circulation, camera capture, and separate abnormal fluorescence patterns including leakage, staining, blockage, and nonperfusion
Fluorescein angiography follows dye through retinal circulation to reveal abnormal fluorescence patterns: leakage, staining, blockage, window defects, and nonperfusion.

Key Takeaways

  • Dye injected into arm vein
  • Photographs blood flow in eye
  • Detects leakage and abnormal vessels
  • Skin and urine turn yellow temporarily
  • Important for diagnosing vascular conditions

Why It's Done

What to Expect

Before the Test

  • Pupils dilated
  • IV line placed in an arm vein
  • Tell the staff about any prior reaction to fluorescein or contrast dye, severe allergies, asthma, kidney disease, or pregnancy
  • Pregnancy is generally a relative contraindication; the test is usually deferred unless absolutely necessary
  • Indocyanine green (ICG) angiography - a related test - uses a different dye. The FDA label contraindicates ICG in patients with a known hypersensitivity to indocyanine green itself; some formulations also list caution in patients with documented iodide allergy because the dye contains sodium iodide. Significant liver disease can alter clearance (ICG is hepatically excreted). A history of shellfish allergy is not a reliable predictor of ICG or contrast reactions - that linkage has been retired by allergy and radiology bodies as a clinical myth - but tell your team about any past dye reactions or severe allergies anyway.

During the Test

  • Fluorescein dye injected through the IV
  • Rapid sequence of photos taken
  • Bright flashes of light
  • Photos continue for several minutes
  • Takes 15-30 minutes total

After the Test

  • Skin and urine appear yellow-orange for 24-48 hours
  • This is expected and temporary
  • Stay hydrated to help flush the dye

Risks and Side Effects

Common (mild)

  • Yellow discoloration of skin and urine
  • Brief nausea or warm flushing during injection
  • Mild itching

Less common

  • Vomiting
  • Hives (urticaria)
  • Extravasation - if dye leaks out of the vein, it can cause local pain, skin staining, and rarely tissue necrosis. Tell the technician immediately if you feel a sudden burning at the IV site.

Rare but serious

  • Anaphylaxis and severe allergic reactions including bronchospasm, throat swelling, hypotension, and cardiac arrest. Severe reactions occur in roughly 1 in 1,900 patients; deaths from fluorescein anaphylaxis are very rare (estimated about 1 in 220,000). Photography rooms should have resuscitation equipment available and staff trained to use it.
  • Vasovagal syncope (fainting)
  • Myocardial infarction or cardiac arrhythmia in patients with significant cardiac disease

If you have ever had a serious reaction to fluorescein or other IV contrast, tell your team - alternative imaging (such as OCT angiography, which does not use injected dye) can often answer the same clinical question.

What It Shows

Normal

  • Even filling of vessels
  • No leakage

Abnormal

  • Disc leakage-inflammation or papilledema
  • Delayed filling-poor blood flow
  • Hyperfluorescence-drusen, scars
  • Blocked fluorescence-hemorrhage

Neuro-Ophthalmic Uses

  • Distinguish true disc edema from drusen
  • Evaluate optic nerve ischemia
  • Assess inflammatory conditions
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