ICG Angiography Indications

Indocyanine green angiography (ICGA) uses a dye that binds strongly to plasma proteins and emits in the near-infrared spectrum — this lets it penetrate the retinal pigment epithelium and image the choroidal circulation in a way FFA and OCTA cannot match, which is exactly where ICGA retains an essential, largely unchallenged role.

Key indications

• Polypoidal choroidal vasculopathy (PCV): ICGA remains the diagnostic gold standard, identifying the characteristic polypoidal lesions and branching vascular network essential for distinguishing PCV from typical neovascular AMD — a distinction that materially changes treatment choice
• Occult/indeterminate choroidal neovascularization: where FFA leakage is poorly defined, ICGA can localize a "hot spot" or feeder vessel
• Central serous chorioretinopathy: demonstrates choroidal vascular hyperpermeability and dilated choroidal vessels (pachyvessels) — central to understanding CSCR as a "pachychoroid spectrum" disease
• Choroidal tumors: characterizing choroidal melanoma and hemangioma vascular patterns; helps distinguish choroidal melanoma from nevus and other simulating lesions
• Inflammatory choroidopathies: birdshot chorioretinopathy, serpiginous choroiditis, multifocal choroiditis — ICGA reveals hypofluorescent dark spots corresponding to inflammatory choroidal lesions often invisible or under-represented on FFA
• Choroidal ischemia in conditions such as pre-eclampsia/eclampsia-related choroidopathy

ICGA vs. OCTA for choroidal disease

Unlike FFA, ICGA has not been substantially displaced by OCTA — OCTA's imaging depth and its inability to show true dye leakage/hyperpermeability limit its usefulness for exactly the diseases where ICGA is most valuable (PCV, CSCR pachychoroid assessment, inflammatory choroidopathies). In current practice, ICGA and OCTA are complementary rather than competing: OCTA for structural/flow detail, ICGA for functional leakage and hyperpermeability of the choroidal circulation.

Key reference: fundamentals of ICGA in choroidal vascular disease remain consistent across recent retina imaging literature; PCV and pachychoroid spectrum disease continue to rely on ICGA as the reference standard.