Fundus Autofluorescence (FAF)

Fundus autofluorescence (FAF) is a non-invasive imaging technique that captures the natural fluorescence of lipofuscin and other fluorophores in the retinal pigment epithelium (RPE). It provides valuable information about the health and metabolic activity of the RPE, making it especially useful for monitoring dry age-related macular degeneration (AMD) and other retinal conditions.

Why It's Done

Fundus autofluorescence is performed to:

• Monitor dry AMD and geographic atrophy
• Detect early RPE changes before visible damage
• Track geographic atrophy progression over time
• Evaluate inherited retinal dystrophies
• Assess macular conditions affecting the RPE
• Distinguish between different types of macular disease
• Guide treatment decisions in retinal conditions

What to Expect

Before the Test

• Pupils are typically dilated
• No special preparation otherwise
• No dye injection needed (unlike fluorescein angiography)

During the Test

1. Sit with chin on the chin rest of the imaging device
2. Look at a fixation target
3. The camera illuminates the retina with a specific wavelength of light
4. Natural fluorescence from the RPE is captured
5. Multiple images may be taken
6. Both eyes are typically imaged
7. Takes approximately 5-10 minutes

After the Test

• No recovery time (beyond normal dilation effects)
• Results available immediately
• Can resume normal activities

Understanding Results

Normal Autofluorescence

• Even, moderate background fluorescence across the macula
• Dark area at the fovea (center of macula) due to macular pigment
• Dark optic disc and blood vessels (no RPE at these locations)

Abnormal Patterns

Increased Autofluorescence (Hyper-AF):

• Bright areas indicate RPE stress or lipofuscin accumulation
• May represent areas at risk for future atrophy
• Seen at the edges of geographic atrophy
• Can indicate active metabolic disturbance

Decreased Autofluorescence (Hypo-AF):

• Dark areas indicate RPE loss or atrophy
• Corresponds to geographic atrophy in dry AMD
• Also seen with pigment changes and scarring

Patterns in Dry AMD:

Pattern	Significance
Bright ring around dark center	Active geographic atrophy (expanding)
Uniform dark area	Established geographic atrophy
Patchy bright areas	RPE stress—at risk for atrophy
Normal background	Stable disease

FAF in Dry AMD Monitoring

Why It's Important

• Geographic atrophy appears as sharply defined dark areas
• The bright border around atrophy predicts progression rate
• Serial imaging tracks how fast atrophy is expanding
• Helps determine treatment timing and response

Complementary to OCT

• FAF shows the extent of RPE damage (en face view)
• OCT shows the depth and layers affected (cross-section)
• Together, they provide comprehensive monitoring

FAF vs. Other Retinal Imaging

Test	What It Shows
FAF	RPE metabolic health and lipofuscin
OCT	Retinal layer structure and thickness
Fundus photography	Surface appearance of the retina
Fluorescein angiography	Blood flow (requires dye injection)

Frequently Asked Questions

Is FAF the same as fluorescein angiography?

No. FAF captures the retina's natural fluorescence without any dye injection. Fluorescein angiography requires injecting fluorescein dye into a vein to visualize blood flow. They provide different information.

Does FAF hurt?

No. FAF is completely painless. It's similar to having a retinal photograph taken. The bright flashes of light may be briefly uncomfortable, especially with dilated pupils.

How often should I have FAF imaging?

For dry AMD monitoring, typically every 6-12 months, though your doctor will determine the best schedule based on your condition's progression rate.

Can FAF detect wet AMD?

FAF is primarily used for dry AMD and geographic atrophy. While it may show some changes in wet AMD, OCT and fluorescein angiography are better for detecting and monitoring wet AMD.

What if the test shows increased autofluorescence?

Increased autofluorescence suggests RPE stress and may indicate areas at risk for future atrophy. Your doctor may monitor these areas more closely and discuss strategies to slow progression.