Fluorescein Angiography

Excerpt

Fundus fluorescein angiography (FFA) and its clinical role in ophthalmology were discovered by two medical students, Herald Novotny and David Alvis. Flocks and colleagues had earlier experimented with intravenous injection of fluorescein in cats to study retinal circulation. However, when the same was attempted in humans, insufficient lighting of the fundus camera and the absence of a barrier filter prevented them from getting serial images of the fundus to measure the circulation time. With time, fundus camera technology improved.

Novotny and Alvis used the new fundus camera and two different filters, blue and green, to image the fluorescence of the dye. They successfully got the first fluorescein angiogram images, which were reported in their published paper in 1961. FFA allows the assessment of the anatomy, physiology, and pathology of the retinal and choroidal vasculature. Sodium fluorescein is an orange water-soluble dye. It has a low molecular weight of 376.3 Da. It remains primarily bound to proteins (80%) in the blood. The retinal vascular endothelium and the retinal pigment epithelium (RPE) act as barriers and do not allow the diffusion of the dye. However, the choriocapillaris allows it to diffuse freely. It is excreted in the urine over 24 to 36 hours and is responsible for the discoloration of urine. It absorbs light in the range of 465 to 490 nm (blue light) and emits light in the range of 520 to 530 nm (green light).

FFA is a diagnostic procedure where a series of photographs of both eyes are taken after injecting sodium fluorescein intravenously. Interpretation and understanding of FFA help in the accurate diagnosis and evaluation of various pathologies. This review also discusses the complications and the role of the interprofessional approach in managing patients undergoing FFA.