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FFA

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.

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FFA

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  1. FFA Dr Aaron Ng

  2. FFA Principles • Fluorescence • Stimulated by light of shorter wavelength • Emission of light of longer wavelength • Flurescein • Excitation peak 490nm • Emit light of about 530nm

  3. FFA Principles: Filters

  4. 5 Phases of Angiogram 1. Choroidal (Pre-arterial): 9-15 sec

  5. 5 Phases of Angiogram 2. Arterial phase: 1 sec after choroidal phase

  6. 5 Phases of Angiogram 3. Arterio-venous (capillary) phase: early venous laminar flow

  7. 5 Phases of Angiogram 4a. Venous phase: Laminar venous flow

  8. 5 Phases of Angiogram 4b. Venous phase – complete filling • Max perifoveal capillary filling – 20-25 sec • First pass of fluorescein circulation – 30 sec

  9. 5 Phases of Angiogram 5. Late (recirculation) phase • Absent after 10 min

  10. 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

  11. Foveal dark appearance • Foveal avascular zone • High density of xanthophyll at the fovea • Foveal RPE larger and rich in melanin and lipofuscin

  12. Causes of hyperfluorescence • Autofluorescence • Pseudofluorescence • RPE window defect • Dye pooling • Dye leaking • Tissue staining-disc, drusen, chorioretinal scar

  13. Autofluorescence Optic disc drusen

  14. Autofluorescence Lipofuscin

  15. Autofluorescence Angioid streaks

  16. RPE window defect Atrophic ARMD

  17. Dye pooling Subretinal - CSCR

  18. Dye pooling Sub-RPE - PED

  19. Dye leaking Proliferative DR Cystoid Macula Oedema

  20. Late staining

  21. 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

  22. Pre-retinal lesions Blockage to all fluorescence

  23. Intraretinal lesions Hard exudates Intraretinal haemorrhages

  24. 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 • Choroidallesions • Filling defects • Vascular occlusions • Loss of vascular bed (myopic degen, choroidaeraemia)

  25. Increased RPE density CHRPE

  26. Choroidal naevus

  27. Filling defects Capillary drop – out in DR (vascular occlusion) Choroidaeraemia (loss of vascular bed)

  28. CNVM subtypes

  29. Classic

  30. Atypical classic

  31. Occult

  32. Minimally classic

  33. 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

  34. ICGA Principles • Infrared excitation (805nm) • Infrared emission (835nm)

  35. 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

  36. Causes for hyperfluorescence • “Window defect” • Retinal or choroidal vessel leakage • Abnormal retinal or choroidal vessels

  37. 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

  38. Clinical indications • PCV • CSCR • Posterior uveitis (extent of disease involvement) • Breaks in Bruch’s (lacquer cracks, angiod streaks) • Contraindication for FFA

  39. CSCR FFA ICGA

  40. CSCR

  41. PCV

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