FFA

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FFA Dr Aaron Ng

description

FFA. Dr Aaron Ng. FFA Principles. Fluorescence Stimulated by light of shorter wavelength Emission of light of longer wavelength Flurescein Excitation peak 490nm Emit light of about 530nm. FFA Principles: Filters. 5 Phases of Angiogram. 1. Choroidal (Pre-arterial): 9-15 sec. - PowerPoint PPT Presentation

Transcript of FFA

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FFA

Dr Aaron Ng

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FFA Principles

• Fluorescence– Stimulated by light of shorter wavelength – Emission of light of longer wavelength

• Flurescein– Excitation peak 490nm– Emit light of about 530nm

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FFA Principles: Filters

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5 Phases of Angiogram

1.Choroidal (Pre-arterial): 9-15 sec

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5 Phases of Angiogram

2.Arterial phase: 1 sec after choroidal phase

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5 Phases of Angiogram

3.Arterio-venous (capillary) phase: early venous laminar flow

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5 Phases of Angiogram

4a.Venous phase: Laminar venous flow

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5 Phases of Angiogram4b.Venous phase – complete filling

•Max perifoveal capillary filling – 20-25 sec

•First pass of fluorescein circulation – 30 sec

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5 Phases of Angiogram

5. Late (recirculation) phase

•Absent after 10 min

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Timing of FFA phases• Arm to retina (ONH): 7-12s• Posterior ciliary artery 9s• Choroidal flush, cilio-retinal artery 10s• Retinal arterial phase 10-12s• Capillary transition phase 13s• Early venous/lamellar/a-v phase 14-15s• Venous phase 16-17s• Late venous phase 18-20s• Late phase 5-15 min

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Foveal dark appearance

- Foveal avascular zone- High density of xanthophyll at the fovea- Foveal RPE larger and rich in melanin and

lipofuscin

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Causes of hyperfluorescence

1. Autofluorescence2. Pseudofluorescence3. RPE window defect4. Dye pooling5. Dye leaking6. Tissue staining-disc, drusen, chorioretinal

scar

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Autofluorescence

Optic disc drusen

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Autofluorescence

Lipofuscin

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Autofluorescence

Angioid streaks

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RPE window defect

Atrophic ARMD

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Dye pooling

Subretinal - CSCR

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Dye pooling

Sub-RPE - PED

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Dye leaking

Proliferative DR

Cystoid Macula Oedema

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Late staining

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Causes for hypofluorescence

• Masking of retinal fluorescence– Pre-retinal lesions block all fluorescence– Deeper retinal lesions e.g. intraretinal

haemorrhages and hard exudates block only capillary fluorescence

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Pre-retinal lesions

Blockage to all fluorescence

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Intraretinal lesions

Hard exudates Intraretinal haemorrhages

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Causes for hypofluorescence

• Masking of background choroidal fluorescence– Conditions that block retinal fluorescence– Conditions that block only choroidal

• Sub-retinal or subRPE lesions• Increased RPE density• Choroidal lesions

• Filling defects– Vascular occlusions– Loss of vascular bed (myopic degen, choroidaeraemia)

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Increased RPE density

CHRPE

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Choroidal naevus

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Filling defects

Capillary drop – out in DR (vascular occlusion)

Choroidaeraemia (loss of vascular bed)

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CNVM subtypes

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Classic

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Atypical classic

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Occult

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Minimally classic

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Indocyanine Green Angiography

• Advantages over FFA– Study of choroidal vasculature otherwise

prevented in FFA due to RPE blockage– Near-infrared light utilised penetrates melanin,

xanthophylls, exudates and subretinal blood– Infrared is scattered less cf visible light, thus

suitable in eyes with media opacities– 98% ICG molecules bound to protein, thus

remaining in the blood vessels

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ICGA Principles

• Infrared excitation (805nm)• Infrared emission (835nm)

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Phases of ICGA• Early phase (first 60 sec

post injection) – choroidal arteries

• Early mid phase (1-3 min) – choroidal veins and retinal vessels

• Late mid phase (3-15 min) – choroidal vessels facing but retinal vessels are still visible

• Late phase (14-45 min) – hypofluorescent choroidal vessels and gradual fading of diffuse hyperfluorescence

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Causes for hyperfluorescence

• “Window defect”

• Retinal or choroidal vessel leakage

• Abnormal retinal or choroidal vessels

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Causes for hypofluorescence

• Blockage– Pigment, blood, fibrosis, infiltrate, exudate, serous

fluid– PED are predominantly hypofluorescent on ICGA

as cf FFA

• Filling defect– Vascular occlusion– Loss of choroidal or retinal circulation

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Clinical indications

• PCV• CSCR• Posterior uveitis (extent of disease

involvement)• Breaks in Bruch’s (lacquer cracks, angiod

streaks)• Contraindication for FFA

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CSCR

FFA ICGA

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CSCR

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PCV