Fluorescein angiography of the corneal limbus--drug effects on capillary blood flow.

By means of fluorescein angiography, plasma flow through the capillaries at the limbus corneae is demonstrated. The number of stained capillaries at a given time served as a measure of capillary perfusion. Even without drug the entire capillary system is perfused at least by plasma. Tolazoline enhanced the velocity of perfusion (P = 2alpha less than 0.01), epinephrine caused a marked capillary constriction (P = 2alpha less than 0.01), as well as--to a lesser extent--did dexamethasone (P = 2alpha less than 0.05). Dionine caused hyperemia, but the data varied much more than after tolazoline. In addition, dionine enhanced the dye leakage from the vessels.