Unit 3 - FFA/ICG/FAF Flashcards
What do FFA’s look at?
Retinal vasculature
What do ICG images look at?
Choroidal blood flow
What wavelength excites NaF and what wavelength does it emit at?
Blue light (465-490)
Emits yellow-green (520-530)
What wavelength does ICG absorb and then emit?
Near IR range (790-805)
Fluoresces at (830nm)
What does NaF bind to?
Serum albumin with remaining free fluorescein being blocked by blood-ocular barrier. (choriocapillaris has fenestrations so will leak it)
What does ICG bind to?
98 % protein bound, mainly to large sized proteins. e.g. globulins, albumin and lipoproteins
What 6 risks are associated with FFA?
Hot flushes
Local erythema (sunburn)
Anaphylactic shock
Shortness of breath
Nausea
Vomiting
What 6 risks are associated with ICG?
- Hot flushes
- Local erythema (sunburn)
- Anaphylactic shock
- Shortness of breath
- Sore throat
- Urticaria
What contraindications are there to ICG and FFA?
Shellfish or iodine allergy
What % of NaF is used
20% intravenously
What dosage of ICG is used?
What is the maximum safe dose?
40mg in 2mL
5mg/Kg
What is the appearance of the disc in ICG, FFA, FAF and red free?
FFA - light
Red free - light
FAF - dark
ICG - dark
What type of pattern would you see in FFA with a scar?
Staining
What is the definition of FFA leakage?
Pattern that increases in size and intensity as the study continues.
What is the definition of FFA pooling?
Pattern that increases in intensity but not size e.g. PED
What causes are there of blocked FFA images?
- Cataract
- VH
- Retinal Haems
What are the four phases of FFA and their times?
- Choroidal flush (8-12secs)
- Arteriovenous phase (11-18secs) Retinal arteries
- Lamellar venous phase ( 15-22secs) Retinal veins in lamellar patter
- Maximal flourescence (22-30 secs)
What are the three phases of ICG and their times?
1.Early phase (0-3mins), choroid hyperflouresces
2. Intermediate phase (3-10mins), maximal fluroscence
3. Late phase (28-30 mins), large choroidal vessels appear dark against the bright stromal flourescence
What does FAF look at?
Evaluation of RPE
Which pigment causes autoflourscence?
lipofuscin
What light is used to look at FAF?
Blue laser (488nm) observed using a 500nm filter.
What do the optic disc and blood vessels look like in FAF?
Dark
What does hypofluorescence in FAF indicate?
Reduced metabolic demand in RPE
What does hyperfluorescence in FAF indicate?
Increased metabolic demand e.g.e inflammation
What does increase flourescence at the edge of a dark area in FAF indicate?
Increasing GA
What machine produced blue light FAF and which green?
Spectralis = blue
Optos - green
Which vein is fluorescein injected into?
Antecubital vein
How is ICG excreted and what patients does this stop from having it?
Liver, not suitable for patients in liver failure
