Introduction to fundus fluorescein and indocyanine green angiography

1. FFA/ICG
Haitham Al Mahrouqi
Oman Medical Speciality Board
Sept 2017

2. Acknowledgment/References
• Dr Al Yaqdhan Al Ghafri presentation
• Dr Sawsan Nawilaty (AAO 2011)
• AAO BCSC 2015, Retina and vitreous
• Ophthalmology by Yanoff&Dukar
• Retina by Ryan
• Retinal Angiography and Optical Coherence
Tomography (Arevalo [Editor])
• Google!

3. Definition
• Definition: Fluorescein angiography (FA) is a
diagnostic technique that uses intravenous
fluorescein dye to allow the sequential
visualization of the blood flow
simultaneously through retinal, choroidal
and iris tissue.

4. Concept
• Fluorescent property Sodium fluorescein
• Means: the ability of certain molecules to emit
light of longer wavelength when stimulated
by light of shorter wavelength.

6. Question?
• What is the excitation
wavelength and the
emitted wavelength in
FFA?
– Excited with blue light
490nm
– Emit green light 530nm

7. Sodium Fluorescein
• A water-soluble dye of an orange-red crystalline
hydrocarbon.
• When injected intravenously, remains largely
intravascular and circulates in the blood stream.
• 80% of fluorescein molecules bind to serum proteins
(albumin), the residue remaining unbound. Only the
unbound molecules are available for fluorescence.
• It undergoes both renal and hepatic metabolism and is
excreted in the urine over 24–48 hours.

8. Sodium Fluorescein
Absolute contraindication:
• Fluorescein allergy
Relative contraindications:
• History of a severe reaction to any allergen is a strong
relative
contraindication.
• Renal failure (lower the fluorescein dose if angiography
is necessary)
• Pregnancy: Although no reported birth defects.
• Moderate-severe asthma
• Significant cardiac disease.

9. Sodium Fluorescein
• Discolouration
of skin and urine
(invariable)
Yanoff

10. The procedure
1. Both pupils are dilated
2. The patient is seated at the camera and IV cannula is inserted in antecubital fossa.
3. Coloured funds photos, red-free photos +/- autofluorescence are taken.
4. Sodium fluorescein is injected 5 ml of 10% solution, or 2.5 ml of 25% solution
(15mg/kg).
5. Images are taken in the following order:
• Early rapid-sequence photographs (1 second intervals for 25–30 seconds).
• Less rapid sequences between 5 and 10 min.
• Late images at 10–20 minutes

11. What is the use of red-free photos?
• Better visualizing of the
retinal vasculature and the
vitreoretinal interface (e.g.
ERM)

12. What is the use of autofluorescence?
• Autofluorescence describe
the appearance of apparent
hyperfluorescence in the
absence of fluorescein.
• It is an imaging modality of
the RPE (lipofusin
autoflouresce).
• Described as:
– Hyperautofluoresence
– Hypoautofluorescence

13. Examples
• Stargardt disease

14. Examples
• CSR • Optic disc drusen

15. What is pseudofluorescence?
• Fake fluorescence
• Filters problem

16. Anatomical consideration
• Choroidal vasculature
– 3 layers
– Choriocappilaris are
fenestrated. They are
organised in lobules.
Supply the outer 1/3 of
retina.
– RPE makes up the outer
blood retinal barrier.

17. Anatomical consideration
• Retinal vessels:
– non-fenestrated (do not leak)
– Inner blood retinal barrier is
made up by the tight
junctions of the capillary
network with pericytes.
– Supply the inner 1/3

18. Anatomical consideration
• The choroid fills up first due to
the shorter route (1 second
before retinal arteries)
• The retinal arteries fill up in 1
second (hence the early rapid-
sequence photographs (1
second intervals for 25–30
seconds).

19. The procedure
1. Both pupils are dilated
2. The patient is seated at the camera and IV cannula is inserted in antecubital fossa.
3. Coloured funds photos, red-free photos +/- autofluorescence are taken.
4. Sodium fluorescein is injected 5 ml of 10% solution, or 2.5 ml of 25% solution
5. Images are taken in the following order:
• Early rapid-sequence photographs (1 second intervals for 25–30 seconds).
• Less rapid sequences between 5 and 10 min.
• Late images at 10–20 minutes

20. Choroidal phases
Arm-Choroid time: 8-15s
Phases:
• Early
• Patchy choroidal filling
• Choroidal flush
• Recirculation phase

21. Choroidal journey
Early
• Dye in the large
vessels before
leaking into the
choroidal stroma
from the CC.

22. Choroidal journey
Patchy choroidal
filling
• Accounted by the
mosaic lobular
pattern of the CC.

23. Choroidal journey
Choroidal flush (20-25s)
• Homogenous
fluorescence of the
choroid, due leaked
fluorescein in the
stroma from the CC.

24. Choroidal journey
Recirculation phases
Less intense fluorescence Clearance from the large
choroidal vessels makes
them silhouette darkly
Clearance from the CC,
back to “patchy choroidal
filling”!

25. Retinal journey
Arm-retina time ≈ 13s
Phases
• Pre-arterial
• Arterial (1s)
• Arteriovenous (8-12s)
– Capillaries phase
– Laminar flow (early venous phase)
• Venous phase (12s)
• Recirculation
– Early (30s-5mins)
– Late (10-20mins)

26. Retinal journey
Pre-arterial
Cilioretinal artery present in 30%
of population comes from the
posterior ciliary artery.
- Which choroidal phase is this?
Patchy choroidal filling

27. Retinal journey
Arterial
• Fills up in 1s

28. Retinal journey
Early arteriovenous (Retinal
capillaries phase)
• Complete arterial filling, no dye in
veins, 1-3 sec.

29. Retinal journey
Late arteriovenous (Laminar
flow).
• Dye appears in retinal venules
entering along venous walls

30. Retinal journey
Venous phase (12s)
• When veins are evenly filled.
Homogeneous hyperfluorescent
background with dye equally
distributed in retinal arterioles,
capillaries, venules and choroid.
• Best to visualize the foveal avascular
zone (FAZ).

31. FAZ
• FAZ corresponds to the
foveola (350-500um)
• Dark because:
– Avascular
– Densely packed and tall RPE
– Xanothophyls
• Ischaemic macula if FAZ >
1000um

32. Retinal journey
Early recirculation
phase (30s-5mins)
• Veins brighter than
arteries
• Best phase for
detecting staining.

33. Retinal journey
Late recirculation phase
(10-20mins)
• Fading fluorescence.

34. Optic disc
• Stains with FFA due
to staining of the
lamina cribrosa and
from the posterior
ciliary arteries.

35. Abnormal FFA
• Hyperfluorescence
– Leaking
– Window defect
– Pooling
– Staining
• Hyporfluorescence
– Blockage
– Vascular filling defect/capillary dropout.

36. Abnormal FFA
Hyperfluorescence: Leaking
Extravasation of dye due to
incompetent blood
retinal barriers.
• Pattern: early continuous increase in
fluorescence In intensity and/or size
• Margins: fuzzy
• Level: intravitreal, intraretinal,
subretinal

37. Abnormal FFA
Hyperfluorescence: Leaking
Example: Leaking microaneurysm

38. Abnormal FFA
Hyperfluorescence: Leaking
Example: Leaking CNVM

39. Abnormal FFA
Hyperfluorescence: Window defect
Increased transmission of the normal
choroidalfluorescence (Atrophic RPE
/reduced RPE pigment)
• Pattern: parallels choroidal
fluorescence
• Size: no change
• Margins: distinct
• Level: subretinal (RPE)

40. Abnormal FFA
Hyperfluorescence: Pooling
Pattern:
• Steady increase in the
hyperfluorescence intensity
• Stable size
• Distinct margins
PED

41. Abnormal FFA
• Hyperfluorescence: Staining
Leakage into tissue
Pattern: steady increase in intensity
• Size: stable
• Margins: distinct
• Level: retinal or subretinal
Staining
drusen

42. Abnormal FFA
• Hyporfluorescence: Blockage

43. Abnormal FFA
• Hyporfluorescence: Vascular
filling defect/capillary dropout.
Capillary
dropout in
BRVO

44. RPE is a screen
Dampens transmission of choroidal
fluorescence (melanin acts as a curtain).
• How can we then image the choroid better?

45. Indocyanine green angiography
• First used in cardiology to measure cardiac
output in 1957
• Large molecular weight compound
• 98% bound to plasma globulins.
• Metabolised in the liver.

46. Indocyanine green angiography
• Does not leak through the fenestrations of the CC.
Therefore perfect for imaging the choroidal
vasculature.
• Its maximal peak of absorption is at 790 to 805nm
and has a peak emission of 835 nm.
• The infra-red light can cross through the RPE.
• Poor efficacy in fluorescence – only 4%, thus poor
resolution.

47. Indocyanine green angiography
• Contraindication
- Contraindicated in iodine allergy
- Patients with liver disease
- Patients taking metformin (precipitates lactic acidosis)
- Pregnancy
• Adverse events (less than fluorescein):
- Used with caution in patients with shellfish allergy.
- Nausea and vomiting
- Anaphylaxis
- Death

48. Procedure
• Similar to FFA.
• Fundus camera must be equipped with infra-red
light.
• Inject 25mg in 5 mls
• Can be done sequentially with FFA
• Image acquisition: 10 images in the first 30s and
then every 15s for the first 5mins and then delayed
at 10mins, 20mins and 40mins.

49. Image acquisition
• Camera: Fundus
camera can be used
with filters however,
newer technologies
which block
reflections give
better resolution.
Visupac, Ziess

50. Indications
• AMD
• Choroidal polypoidal vasculopathy
• Retinal Angiomatous Proliferation
• Choroidal tumours
• Chorioretinal Inflammatory Diseases

51. Indocyanine green angiography
• Phases:
– Early : 0-3mins
– Mid (3-15mins): Fading away
– Late (15-40mins): Staining of the extrachoroidal tissue
• Interpretation: Same as FFA
– Hypocyanescence: Blockage and filling defects
– Hypercyanescence: Leakage, staining, pooling and window
defects

52. Indocyanine green angiography (Early phase)

53. Example:
AMD

54. Example:
AMD

55. Example:
PCV

56. Example:
Birdshot

57. Example:
Birdshot

58. Thank you