Indocyanine green angiography is an imaging test that uses indocyanine green dye and near-infrared light to visualise the choroidal circulation beneath the retina. It complements fluorescein angiography by better showing deeper vessels.
Procedure
The dye is injected into a peripheral vein, and a specialised camera records images as it circulates through the ocular vasculature. Near-infrared wavelengths penetrate pigment and fluid more effectively, enhancing choroidal detail.
- Requires intravenous access and monitoring for rare allergic reactions
- Images capture early filling, mid-phase, and late staining patterns
- Dye is protein-bound, giving different leakage characteristics to fluorescein
- Contraindicated in certain iodine or shellfish allergies in some protocols
Clinical Uses
Indocyanine green angiography is particularly useful in conditions such as polypoidal choroidal vasculopathy, central serous chorioretinopathy, and occult choroidal neovascularisation. It helps guide targeted treatments including photodynamic therapy.
- Reveals choroidal aneurysms, plaques, and network configurations
- Can clarify ambiguous findings on fluorescein or OCT
- Important for planning and monitoring therapy in selected macular diseases
- Used mainly in specialist retinal centres
