Fundus photography and fluorescein angiography Fluorescein angiography

Fluorescein angiography is a clinical diagnostic test procedure in which rapid-sequence photography is performed after intravenous injection of sodium fluorescein. The procedure allows the documentation of the retinal circulation. Of equal importance is the ability of the angiogram to outline the entire retinal vascular bed. Previous clinical methods of examination of the fundus enabled the physician to effectively see only a portion of the retinal vasculature, namely the larger blood vessels. Due to the miniscule caliber of the retinal capillaries, much of the more important structures could not he visualized. Now, with the use of fluorescein dye, combined with retinal fluorescence photography techniques, these mi crovascular structures may he clearly demonstrated. The angiogram is helpful in the evaluation and demonstration of systemic diseases such as diabetes and hypertension through its ability to show the changes that may take place in the microvascular structures. Differential diagnoses of a number of eye conditions such as circulatory and inflammatory disorders are made possible due to time differences in the appearance of the dye in certain areas of the retina and to dye flow or leak patterns which are unique to certain disease entities. The use of fluorescein dye in ophthalmology is not a recent development but dates back as far as 1881, ten years after the substance was first synthesized by Von Baeyer (Maumenee, 1968). At that time Erhlich observed that after dye was injected into the blood stream, the dye appeared in the anterior chamber. This disclosure led others to make use of the substance as a "marker" in the study of the circulation of the aqueous humor, and by 1900 many investigators had done extensive work with the dye. Burke (1910) also used fluorescein dye to study fundus pathology by administering five grams of the dye to adults in coffee and two to three grams to children. With these concentrations, he was able to observe fluorescence in retinal and choroidal lesions with ordinary illumination. The conditions of inflammatory lesions, chorioretinitis and optic neuritis were reported as appearing heavily stained; healthy retinas did not stain. Fisher (1929) reported his observations of dynamic blood flow through the iris vessels of a rabbit after injection of fluorescein dye. Maumenee (1955) gave an intravenous injection of fluorescein to study a choroidal hemangioma by ophthalmoscopy, and later he and MacLean (1960) applied the same technique of fluorescein angioscopy in the differential diagnosis of malignant melanomas and choroidal hemangiomas.