Transcript FUNDUS ANGIOGRAPHY 1. Fluorescein (FA) • General principles • Excitation and emission • Filters • Photographic technique • • • • Phases of normal angiogram Causes of dark appearance of fovea Causes.

FUNDUS ANGIOGRAPHY
1. Fluorescein (FA)
• General principles
• Excitation and emission
• Filters
• Photographic technique
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Phases of normal angiogram
Causes of dark appearance of fovea
Causes of hyperfluorescence
Causes of hypofluorescence
2. Indocyanine green (ICG)
• General principles
• Phases of normal angiogram
General principles of FA
Fluorescein
85% bound to serum proteins
15% unbound ‘free’ fluorescein
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Inner blood-retinal barrier
(retinal capillaries)
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Impermeable to fluorescein
Outer blood-retinal
barrier (zonula occludens)
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Impermeable to fluorescein
Choriocapillaris
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Permeable only to ‘free’ fluorescein
Excitation and emission
Filters
Photographic technique
1. Take red-free photograph
2. Inject rapidly 5 ml of 10% solution
3. Take photographs at 1 sec intervals
between 5-25 sec after injection
4. Take photographs after 10 min and
20 min, if appropriate
Phases of normal FA
Arterial
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Arterial filling
Arteriovenous
(capillary)
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Almost complete
venous filling
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Very early lamellar
venous flow
Mid-venous
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Early venous
Late venous
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Complete venous
filling
Marked lamellar venous flow
Late
Progressively weaker fluorescence
• Staining of disc
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Causes of dark appearance of fovea
Avascularity
Blockage of background
choroidal fluorescence by:
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Increased density of xanthophyll
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Large RPE cells with more
melanin
Causes of hyperfluorescence ( 1 )
RPE ‘ window’ defect
Pooling of dye
RPE atrophy
Under RPE
Under sensory retina
(bull’s eye maculopathy
(pigment epithelial detachment)
(central serous retinopathy)
Causes of hyperfluorescence (2)
Leakage of dye
Into sensory retina
From new vessels
(cystoid macular oedema)
(choroidal neovascularization
Prolonged dye retention
( staining )
Associated with drusen
Causes of hypofluorescence (1)
Blocked retinal or choroidal fluorescence
• Blood under retinal pigment
epithelium
• Abnormal
material
• Increased
pigment
• Preretinal or intraretinal blood
Causes of hypofluorescence (2)
Vascular occlusion
Capillary non-perfusion
(venous occlusion)
Loss of vascular tissue
Choroideremia or high myopia
General Principles of ICG Angiography
1. Binding
98% bound to proteins
Less leakage from choriocapillaris
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2. Fluorescence
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Much less than fluorescein
Excitation peak 800 nm
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Emission at 835 nm
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3. Filters
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Infrared barrier and excitation
4. Safer than fluorescein
Phases of normal ICG angiogram (1)
Early (20 sec)
Disc hypofluorescence
• Poor perfusion of vertical
(watershed) zone near disc
• Prominent filling of choroidal arteries
• Early filling of choroidal veins
• Filling of retinal arteries but not veins
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Early middle (3 min)
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Filling of watershed zone
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Fading of choroidal arterial filling
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Prominent filling of choroidal veins
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Filling of retinal arteries and veins
Phases of normal ICG angiogram (2)
Late middle (6 min)
Reduced filling of choroidal vessels
• Diffuse hyperfluorescence due to
diffusion of dye from choriocapillaris
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Persistent filling of retinal vessels
Late (21 min)
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Large choroidal and retinal vessels are
empty
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Diffuse background hyperfluorescence