Indocyanine green angiography (ICGA) is a diagnostic procedure used to examine choroidal blood flow and associated pathology. Indocyanine green (ICG) is a water soluble cyanine dye which shows fluorescence in near-infrared (790–805 nm) range, with peak spectral absorption of 800-810 nm in blood. The near infrared light used in ICGA penetrates ocular pigments such as melanin and xanthophyll, as well as exudates and thin layers of sub-retinal vessels. Age-related macular degeneration is the third main cause of blindness worldwide, and it is the leading cause of blindness in industrialized countries. Indocyanine green angiography is widely used to study choroidal neovascularization in patients with exudative age-related macular degeneration. In nonexudative AMD, ICGA is used in classification of drusen and associated subretinal deposits. Indications Indications for indocyanine green angiography include: Choroidal neovascularisation (CNV):Indocyanine green angiography is widely used to study choroidal neovascularization in patients with exudative age-related macular degeneration. In ICGA, CNV is seen as hyperflourescent spot or plaque. It is also useful in diagnosing and classifying CNV associated to serous pigment epithelial detachments in Nonexudative macular degeneration. Idiopathic polypoidal choroidal vasculopathy (IPCV) Pigmented choroidal melanomas Choroidal haemangioma: ICGA can be used to differentiate choroidal haemangioma from other intraocular tumors. Choroiditis: In multifocal choroiditis, lesions are visualized as hypoflourescent spots. Chorioretinopathy: In Central serous chorioretinopathy, using ICGA multifocal areas of choroidal hyperpermiability can be visualized. In birdshoot chorioretinopathy, lesions appear as symmetrical round or oval hypoflourescent spots. ICGA allows better visualization of lesions in serpiginous chorioretinopathy, punctate inner chorioretinopathy, acute zonal occult outer retinopathy etc. In multiple evanescent white dot syndrome, numerous hypoflourescent spots can be visualized using ICGA. Pigmented epithelial detachment Retinal angiomatous proliferation (RAP) Chorioretinal atrophy: ICGA help evaluating different stages of chorioretinal atrophy. Anterior uveitis: ICGA is rarely indicated in anterior uveitis, but it might be used to find out associated choroidal pathology. Stargardt disease: Numerous hypoflourescent spots are seen in ICGA. Angioid streaks: ICGA can be used for diagnosing angioid streaks and their associated ocular pathologies. Vogt–Koyanagi–Harada disease (VKH): ICGA is useful in diagnosing VKH. In VKH, delay in filling of the choriocapillaris along with larger choroidal vessel perfusion and multiple hypofluorescent spots are visible with ICGA. Sympathetic ophthalmia: Sympathetic ophthalmia is a bilateral, granulomatous form of uveitis. In sympathetic ophthalmia, numerous dark spots may be visible during the intermediate phase of ICGA. Procedure Fundus camera-based indocyanine green angiography techniques and scanning laser ophthalmoscope-based indocyanine green angiography techniques