Fluorescein Angiography for the CPOA Exam

What Is Fluorescein Angiography?

Fluorescein angiography (FA) is a diagnostic imaging procedure that uses intravenous sodium fluorescein dye to photograph the circulation of the retinal and choroidal blood vessels. It is the gold standard for evaluating vascular diseases of the retina, including diabetic retinopathy, wet macular degeneration, branch and central retinal vein occlusions, and retinal neovascularization.

The test involves injecting fluorescein dye into an arm vein, then taking rapid, sequential photographs of the retina under blue light illumination as the dye passes through the retinal vessels. Areas where vessels leak, are blocked, or have abnormal blood flow are identified by abnormal fluorescein patterns.

Why FA Is Done

• Diabetic retinopathy: Identifies areas of capillary nonperfusion (ischemia), leaking microaneurysms, and neovascularization requiring laser treatment.
• AMD (wet form): Identifies the location and type of choroidal neovascularization (CNV) to guide anti-VEGF treatment decisions.
• Retinal vascular occlusions (BRVO, CRVO): Delineates ischemic zones and guides laser or injection treatment.
• Inflammatory conditions: Detects vascular leakage, cystoid macular edema, and disc leakage in uveitis.

CPOA Role in Fluorescein Angiography

Before the Procedure

• Dilate the patient: Full dilation (pupil 6-8 mm) is required for FA. Instill mydriatic drops (tropicamide 1%, phenylephrine 2.5%) at least 20-30 minutes before the procedure.
• Obtain informed consent: The doctor or nurse obtains consent -- the CPOA ensures the consent form is in the chart.
• Allergy history: Ask explicitly about allergies to fluorescein dye, other dyes, iodine, or contrast agents. Document in the chart and alert the doctor. Patients with prior fluorescein reactions or severe iodine/shellfish allergies may need premedication or the procedure may be contraindicated.
• Establish IV access: In practices where the CPOA is trained and authorized by office policy, an intravenous catheter (butterfly or over-the-needle catheter) is placed in an arm vein. Check your state and practice scope of practice rules -- IV placement may require specific certification.
• Prepare the fluorescein syringe: Typically 5 mL of 10% or 25% sodium fluorescein, prepared and labeled per the doctor's orders.

During the Procedure

• The patient is positioned at the fundus camera with full dilation.
• The doctor or nurse injects the fluorescein rapidly (in 1-2 seconds) while the camera operator begins timing and photography.
• The CPOA may operate the fundus camera, taking rapid-sequence images in the first 30-90 seconds (arterial and early venous phases) and then at intervals for 10-15 minutes.

💡 Clinical Tip: The first photographs after injection are the most critical -- the arteriovenous transit time (how long dye takes to travel from arteries to veins, normally 10-15 seconds) and early filling patterns provide diagnostic information that cannot be recaptured. Prepare for rapid photography by having all settings confirmed before the injection is given.

Adverse Reactions to Fluorescein

Fluorescein is generally safe, but adverse reactions occur in about 1-5% of patients. The CPOA must know these and how to respond:

⚠️ Common Mistake: Failing to warn the patient about skin and urine discoloration before the procedure. When patients are not forewarned, the yellow skin and orange urine that follow fluorescein injection cause significant alarm. Preventing anxiety with a simple pre-procedure explanation is a basic standard of patient care.

Key Takeaways

• Fluorescein angiography uses IV fluorescein dye and sequential retinal photography to evaluate retinal vascular diseases.
• Full dilation is required before FA.
• The CPOA checks for fluorescein/dye allergies, helps prepare the patient, may assist with IV access, and operates the camera.
• Adverse reactions range from common nausea to rare anaphylaxis -- the CPOA must be prepared for all levels.
• Warn all patients about temporary yellow skin discoloration and orange urine before the procedure.
• The early arterial and venous phases (first 30-90 seconds) are the most critical and cannot be repeated -- be camera-ready before injection.