Fluorescein angiography (FA) is a specialized eye imaging test that uses a fluorescent dye (sodium fluorescein) injected into a vein to visualize blood vessels in the retina and choroid. Procedure: pupils dilated; baseline photos taken; fluorescein dye (5 mL typically) injected into arm vein; series of rapid retinal photographs taken as dye travels through retinal blood vessels (about 30 seconds for dye to reach eyes); imaging continues for 5-10 minutes capturing dye filling and leaking phases; late photos at 10-15 minutes. Demonstrates: blood vessel anatomy and integrity; areas of leakage (broken blood vessels); areas of nonperfusion/ischemia (no blood supply); neovascularization (abnormal new vessels); microaneurysms. Total appointment: about 60-90 minutes including dilation. Performed at retina specialist or ophthalmologist office with imaging equipment. Used to evaluate moderate to severe retinopathy and guide treatment. Indications: determine extent of retinal nonperfusion/ischemia (cannot be seen on regular exam); identify and locate microaneurysms or abnormal vessels needing laser treatment; evaluate diabetic macular edema (often combined with OCT); detect neovascularization (abnormal blood vessels — proliferative diabetic retinopathy); plan and guide focal laser photocoagulation; monitor response to anti-VEGF treatment; pre-operative planning for vitreoretinal surgery. NOT used for: routine retinopathy screening (use color photographs or comprehensive exam); mild non-proliferative retinopathy without macular involvement. Increasingly replaced/supplemented by OCT angiography (OCTA) — dye-free; less invasive; lower spatial resolution but no needle/dye risks. Indications for FA narrowing as OCTA improves. Preparation: schedule with someone to drive you home (pupils dilated 4-6 hours afterward affects vision); arrive 15-20 minutes early; bring sunglasses for after; eat normally; take medications as usual. Procedure: pupils dilated with drops (15-20 minutes); brief baseline retinal photos; IV line placed in arm (small needle); fluorescein dye injected over 5-10 seconds; rapid retinal photos begin immediately as dye reaches eyes; you’ll see bright flashes from the camera (uncomfortable but tolerable); imaging continues for 5-10 minutes; late photos at 10-15 minutes; total imaging time about 30 minutes. Possible sensations: brief warmth and unusual taste as dye injected; sometimes nausea (lasts minutes); occasional sneezing. After: yellow tint to skin (lasts 6-12 hours); bright yellow urine (lasts 24-48 hours); pupils stay dilated 4-6 hours.
FA Indications in Diabetic Retinopathy
| Indication | Use |
|---|---|
| Macular edema evaluation | Identify leaking microaneurysms for focal laser |
| Nonperfusion mapping | Document ischemic areas; guide PRP |
| Neovascularization detection | Confirm proliferative diabetic retinopathy |
| Treatment response | Monitor response to anti-VEGF or laser |
| Pre-surgical planning | Map vascular anatomy before vitrectomy |
What FA Shows
| Finding | Significance |
|---|---|
| Hyperfluorescent dots | Microaneurysms (early DR) |
| Leakage of dye | Broken blood vessels; macular edema source |
| Hypofluorescent areas | Nonperfusion/ischemia (severe DR) |
| Lacy hyperfluorescence | Neovascularization (PDR) |
| Dilated capillaries | Foveal avascular zone enlargement |
FA Side Effects and Risks
- Yellow skin tint (lasts 6-12 hours) — common, expected.
- Bright yellow urine (lasts 24-48 hours) — common.
- Pupil dilation aftereffects (4-6 hours).
- Brief warmth and unusual taste during injection (~30%).
- Nausea (~5%) — usually brief.
- Sneezing during injection — common, harmless.
- Vasovagal reaction (lightheadedness, fainting) — rare.
- Hives, itching (~1%).
- Extravasation (dye outside vein) — yellow skin at site for days.
- Severe allergic reaction (anaphylaxis) — about 1 in 200,000.
- Death — extremely rare (~1 in 220,000).
- Emergency equipment and antihistamines available at every facility.
FA vs OCT Angiography (OCTA)
- FA — dye-based; whole retinal vasculature; gold standard; invasive (IV needle, dye).
- OCTA — dye-free; layer-by-layer vascular imaging; non-invasive; takes seconds.
- OCTA limited to macular area in many devices.
- OCTA cannot show leakage (no dye to leak).
- FA still gold standard for leakage assessment.
- OCTA increasingly used for routine vascular assessment.
- Combination of OCT, OCTA, and color photos sufficient for many cases.
- FA reserved for treatment planning and complex cases.
Preparation Checklist
- Bring someone to drive you home.
- Bring sunglasses for after dilation.
- Eat normally before procedure.
- Take medications as usual.
- Bring list of allergies (especially iodine, contrast dye).
- Inform staff if pregnant or possibly pregnant.
- Inform staff of kidney disease.
- Hydrate well before procedure.
- Allow 60-90 minutes total time.
- Wear easy-to-roll-up sleeve.
The Bottom Line
Fluorescein angiography (FA) is a specialized eye imaging test that uses a fluorescent dye (sodium fluorescein) injected into a vein to visualize blood vessels in the retina and choroid. Procedure: pupils dilated; baseline photos taken; fluorescein dye (5 mL typically) injected into arm vein; series of rapid retinal photographs taken as dye travels through retinal blood vessels (about 30 seconds for dye to reach eyes); imaging continues for 5-10 minutes capturing dye filling and leaking phases; late photos at 10-15 minutes. Demonstrates: blood vessel anatomy and integrity; areas of leakage (broken blood vessels); areas of nonperfusion/ischemia (no blood supply); neovascularization (abnormal new vessels); microaneurysms. Total appointment: about 60-90 minutes including dilation. Performed at retina specialist or ophthalmologist office. Used to evaluate moderate to severe retinopathy and guide treatment. Indications: determine extent of retinal nonperfusion/ischemia (cannot be seen on regular exam); identify and locate microaneurysms or abnormal vessels needing laser treatment; evaluate diabetic macular edema (often combined with OCT); detect neovascularization (abnormal blood vessels — proliferative diabetic retinopathy); plan and guide focal laser photocoagulation; monitor response to anti-VEGF treatment; pre-operative planning for vitreoretinal surgery. NOT used for routine retinopathy screening or mild non-proliferative retinopathy without macular involvement. Increasingly replaced/supplemented by OCT angiography (OCTA) — dye-free; less invasive; lower spatial resolution but no needle/dye risks. Preparation: schedule with someone to drive you home; arrive 15-20 minutes early; bring sunglasses for after; eat normally; take medications as usual. Procedure: pupils dilated with drops (15-20 minutes); brief baseline retinal photos; IV line placed in arm; fluorescein dye injected over 5-10 seconds; rapid retinal photos begin immediately; imaging continues for 5-10 minutes; late photos at 10-15 minutes; total imaging time about 30 minutes. Possible sensations: brief warmth and unusual taste as dye injected; sometimes nausea (lasts minutes); occasional sneezing. After: yellow tint to skin (lasts 6-12 hours); bright yellow urine (lasts 24-48 hours); pupils stay dilated 4-6 hours. Side effects: nausea (~5%), itchy skin (~1%), severe reactions (anaphylaxis) rare but possible (1 in 200,000). Contraindications: severe allergy to fluorescein, pregnancy (relative), severe kidney disease (relative). For adults with type 2 diabetes — FA is used when retinopathy treatment decisions need vascular detail; not used for routine screening; discuss with retina specialist if recommended. See our broader diabetic retinopathy guide for context.
