Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PART ONE REVISION. > CLINICAL TECHNIQUES - Flourescein and ICG, > Flashcards

CLINICAL TECHNIQUES - Flourescein and ICG, Flashcards

1
Q

What are the contraindications to ICG? (5)

A
  1. Pregnancy
  2. Seafood Allergy (not in FFA)
  3. Iodide Allergy (not in FFA)
  4. Kidney Failure
  5. Liver Disease (not in FFA)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the contraindications to FFA? (4)

A
  1. Previous allergy to fluorescein
  2. Breastfeeding (not in ICG)
  3. Kidney failure
  4. Pregnancy (relative contraindication)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the side effects of 5-FU during glaucoma filtration surgery?

A

Ischaemic blebs
Hypotony
Suprachoroidal haemorrahge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the wavelengths of sodium flourescein?

A

Absorbs blue light - 465-495nm
Emits green light - 520-530nm

Usually 10%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How much flourescein is bounded to plasma protein?

How much is ICG boudned to plasma protein?

A

80% bound to proteins
98% bound to proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Where can flourescein distribute to?

A

Readily diffuses through the choriocapillaries through fenestrations..

Does not diffuse through retinal vascular endothelium (in RNFL) and RPE due to blood retinal barrier - if there are breakages in RPE or neovascularisations, can pass here.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the mechanism of FFA?

A

White light passes through cobalt blue excitation filter and reach retina and reflect back (blue and green light will reflect back)

Barrier fielter blocks blue light and only allows yellow/green light to exit and give flourescein image.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the different phases of FFA?

A

Choroidal: 10-12 seconds after injection (choroidal flush due to dye leaking through choriocapillaries from long PCAs

Arterial: 1-3 seconds after choroidal phase - can see neovascularisation of the disc

AV phase: Demonstrates laminar flow.

Late phase: Useful to highlight CMO, CSR or occult CNVMs

Later staining of optic disc is normal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the different abnormalities seen in FFA?
(4)

A

Leakage - increasing in hyperflourescence over time.
1. Incompetence of inner/outer Blood retinal barriers
2. Neovascularisation: Defective inner barrier
3. Defective choroidal circulation (AMD)

Window defect: Unmasking of normal choroidal flourescence –> seen early.
1. RPE atrophy

Late Hyperflourescence due to dye staining
1. Drusen
2. Disciform scars

Pseudo-auoflouresence - overlap in transmission of excitation and barrier filters.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

When is ICG used?

A

More information about choroidal circulation
as ICG can penetrate through overlying RPE

  1. Occult/poorly defined CNVM
  2. Polypoidal CNV
  3. Fibrovascular PEDs
  4. Medial opacities/vitreous haemorrhage
  5. Photophobic patients (can’t see infrared but can see visible light)
  6. Inflammatory disease: occult choroidal disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

At what wavelengths does ICG absorb and flouresce?

A

Absorption: 790-805nm
Emission: 770-880nm

Within infrared range of wavelengths and so can penetrate overlying RPE and overlying haemorrhages.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the main side effects of ICG/FFA.

A

FFA: discoloured urine and skin

ICG: discoloured stool as ICG is excreted by hepatobiliary system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

WHen does the early venous phase begin in relation to the choroidal phase?

A

5 seconds after choroidal phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why is the macula darker in arteriovenous phase? (3)

A
  1. Xantophyllic pigment
  2. More pigment in RPE cells
  3. Absence of capillaries in avascular region of fovea.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which arteries fill earlier in arterial phase, nasal or temporal?

A

Nasal arteries fill earlier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Are choroidal arteries straight or tortuous? Are choroidal veins straight or tortuous?

A

Choroidal arteries: tortuous
Choroidal veins: straight

17
Q

How much does sodium fluorescein weigh?

A

376Da

18
Q

How quickly is flourescein metabolised by the liver and excreted by the kidneys?

A

Within 24 hours

19
Q

When are the phases of ICG?

  1. Early phase
  2. Early mid phase
  3. Late mid phase
  4. Late phase
A
  1. Early - 2-60 seconds
  2. Early mid phase - 1-3 minutes
  3. Late mid-phase: 3-15 minutes
  4. Late phase: 15-30 minutes
20
Q

How much does ICG weigh? How much does flourescein weigh?

A

FLourescein: 354 daltons
ICG: 775 daltons

21
Q

What are the differences in SLO imaging vs colour fundus camera imaging?

A
  1. Higher contrast in SLO
  2. Lower spatial and temporal resolution in colour fundus photos
    3.
22
Q

What is the source of autoflouresence?

A

Lipofuscin in the RPE is source of background autofloureseence of retina –> byproduct of phagocytosis of outer segments in the RPE.

23
Q

What does autoflouresence refer to?

A

Emission of intrinsic flouresence by substance subsequent to stimulation by excitation energy

24
Q

What colour light is used for auto-fluorescence?

A

Green.

25
Q

Hypoflourescence in all phases of angiography of ICG indicative of which conditions?

A

Permanent: Atrophic lesions

Reversible: White dot syndromes (MEWDS, APMPPE)

26
Q

Hypoflourescence until intermediate phase of ICG which then become isofluorescent or hyperfluoresent in the late phase are indicative of what conditions?

A
  1. Space-occupying lesions beneath the choriocapillaris
  2. Granulomatous inflammation (VKH, sympathetic ophthalmia, sarcoid, tuberculosis, birdshop chorioretinopathy)
27
Q

The Scanning Laser Ophthalmoscopy machine used to detect autoflourescence –> 1. Uses what wavelength for excitation?

A

488nm

28
Q

Which lesions are typically hyperfluorescent on FFA but hypofluorescent on ICG?

A

PEDs.

29
Q

The auto-flourescence camera reduces interference from which structure?

A

Lens

PART ONE REVISION. (77 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions