The light used for F/A is absorbed by the RPE, and thus can not take imaging of the Choroidal circulation.
Indocyanine green (ICG) is a tricarbocyanine dye that absorbs Infra-Red (non-visible) light. ICG is almost 98% plasma protein bound. This high degree of protein binding results in the tendency for ICG to remain intravascular.
ICG Angiography The Infra-Red wavelenths have the ability to penetrate the retinal layers, enables imaging of the choroidal circulation below the RPE. Thus the image usually take through pigmentation, fluid, or blood in the back of the eye.
ICG enhanced imaging of the choroid for, Ischemic diseases, Tumors, Idiopathic syndromes, and Inflammatory diseases.
Choroidal Malignant Melanoma
The most practical clinical application of the ICG/A has been in those patients with ARMD. ICG/A unique properties mean that areas of CNV beneath Blood, Exudate, or Pigment Epithelial Detachment (PED) can be imaged more readily.
Sub-Retinal Hemorrhage & CNV
PED & CNV
Hemorrhagic PED & CNV
ICG/A complements F/A, which captures blood flow above the RPE. Although ICG/A is not a replacement for F/A, it provides adjunctive information which assists in defining the Choroidal circulatory involvement in Retinal pathology.
F/A & ICG/A are valuable adjunct to diagnosis that supports and enhances, but does Not Replace, standard Clinical Examination.