Thick blood, pigment, scar tissue, or a PED may block fluorescence during angiography and obscure an underlying CNV. ICG angiography, with its longer wavelength fluorescence in the infrared spectrum, may be able to penetrate deeper through heme or pigment to reveal a hot spot that identifies CNV. Because it has 90% protein-binding, it can also differentiate between scar tissue or serous RPE fluid to reveal an active vascular lesion.