Study of late phase fluorescence in the rabbit fundus.

were the first to photograph fluorescence in the ocular fundus after intravenous injection of fluorescein. They studied the characteristics of the passage of fluorescence through the fundus of the eye. These are now well established by serial photographs and cinematography; arterial, venous, and late phases being recognized. A number of ocular conditions have been studied clini- cally in which staining has persisted long after blood fluorescein levels have fallen below the visible threshold. Fluorescein has a small, water-soluble molecule which diffuses readily. It becomes bound to protein slowly and in insignificant amounts when injected intravenously. There is a rapid fall in the plasma concentration of fluorescein and within 10 minutes it has diffused into a volume four times that of the plasma (Dollery, Hodge, and Engel, 1962).