Fundus fluorescein angiography (FFA) is an essential diagnostic method developed to examine retinal blood flow and is indispensable in the diagnosis and follow-up of retinal diseases. By administering fluorescein dye, which fluoresces in yellow-orange under blue light, black-and-white digital photographs are taken of the vascular structures of the retina.
Blue and yellow-green filters are placed on the optical axis of the camera. The blue filter allows only blue light to pass through to the retina, while the yellow-green filter blocks the blue component of the reflected light, ensuring that the camera only captures the image of the fluorescein dye.