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FFA 20% free in plasma Excited by blue light to emit yellow light Cannot diffuse through tight junctions – RPE – Retinal vessel endothelium NB – fluorescein leaks freely into aq/vit therefore white structures pseudofluoresce
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FFA & ICG
Ewan McCallumGHH
15/7/14
Overview
• FFA & ICG– Background– Examples– Background– Examples
FFA
• 20% free in plasma• Excited by blue light to emit yellow light• Cannot diffuse through tight junctions– RPE– Retinal vessel endothelium
• NB – fluorescein leaks freely into aq/vit therefore white structures pseudofluoresce
FFA
• 5 phases– Choroidal – v brief as leaks fast– Arterial – CRA fills 1 sec later– Capillary – peri foveal network most visible due to
luteal pigment. 500micron FAZ– Venous – early laminar flow– Late – 10-15mins dye only left in structures where
it has leaked. Drusen, window defects and inactive scars fade, i.e show up active disease
ICG
• 800nm wavelength, penetrates retinal layers• Tightly bound to plasma proteins so stays in
vessels• Allows better view of choroidal circulation
Polypoidal choroidal vasculopathy
• Sub type of AMD• 15% of all ‘CNV’• Steep walled haemorrhagic PED on OCT• PDT +/- anti VEGF best• Need ICG to diagnose most (wide angle to pick
up more)
Retinal angiomatous proliferations
• Sub type of AMD• Large serous PEDs• extensive areas of small drusen • leak aggressively • Respond poorly to anti VEGF– NB patient expectation
• Up to 100% of fellow eyes affected• 37% within 3 years
MACTEL
• Not an ‘AMD’• Important as does not respond to anti VEGF
CSR
• Can be confused with AMD as exudative maculopathy
• Especially if chronic/recurrent • Chronic can develop into nAMD or IPCV
Diabetes