Transcript FFA & ICG
FFA & ICG Ewan McCallum GHH 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