The last decade has seen renewed interest in topical epinephrine for the treatment of glaucoma. The more frequent use of the gonioprism to distinguish open-angle from angle-closure glaucoma has been an important factor in better defining the use of epinephrine. Tonography and fluorescein-turnover studies have provided some insight into the mode of action of this as well as other agents used in the treatment of glaucoma. In 1951 Goldmann1 concluded from fluorescein-turnover studies that glaucosan decreased intraocular pressure by decreasing the secretion of aqueous humor. Weekers, Prijot, and Gustin,2 in a series of 14 patients with chronic simple glaucoma and pressures less than 34 mm. Hg, demonstrated tonographically that topical epinephrine lowered intraocular pressure in the first 48 hours of its use without altering the facility of outflow. In a second group of 7 patients, however, with tensions greater than 35 mm. Hg, they found that topical epinephrine