Final answer:
Fluorescein angiography is used to measure circulation in the retina of the eye by injecting a fluorescent dye and analyzing the patterns of dye movement in the retinal blood vessels.
Step-by-step explanation:
Fluorescein angiography is used to measure circulation in the retina of the eye. This diagnostic procedure involves injecting a fluorescent dye into a vein and taking photographs as the dye flows through the retinal blood vessels. By analyzing the patterns of dye movement, doctors can identify abnormalities in retinal circulation, such as blockages or leaks.