Immediate effect of epinephrine on aqueous formation in the normal human eye as measured by fluorophotometry

Epinephrine hydrochloride (1%) and an identical-appearing placebo were instilled into the right/left eye pairs (random assignment) of 24 young normal subjects. Aqueous humor flow (measured by fluorophotometry over a 7 hr period), intraocular pressure, and (in 10 subjects) tonographic facility of outflow were measured. The effects of epinephrine were to lower intraocular pressure (2.8 mm Hg +/- 1.9, mean +/- S.D.), raise the facility of outflow (37.4% +/- 21.7), and increase the rate of formation of aqueous humor (18.6% +/- 18.1). By comparing tonographic and fluorophotometric data in the same subjects, it was postulated that epinephrine increases the rate of outflow via the pressure-insensitive (uveoscleral, uveovortex) outflow pathway.