This procedure involves injecting a small bolus of fluorescein (a vegetable dye derivative) into a patient’s arm and photodocumenting, over time, the flow of the fluorescein through the choroidal and retinal vasculature. An exciter filter and a barrier filter are used to allow for the fluorescein to fluoresce and to block out all other wavelengths. Macular edema and vascular abnormalities, such as neovascularization, are commonly assessed by fluorescein angiography.