Fluorophotometric study of epinephrine and timolol in human subjects

The action and interaction of topical 2% epinephrine hydrochloride and 0.5% timolol maleate therapy were studied in 12 normal and 16 ocular hypertensive subjects. Measurements of intraocular pressure, outflow facility, and aqueous secretion by fluorophotometry were made. Uveoscleral outflow values were calculated. Epinephrine, applied topically twice daily for one week, resulted in a decrease in IOP of 3.3 +/- 0.9 mm Hg and an increase in outflow facility of 0.05 +/- 0.01 microL/min/mm Hg, as well as an increase in the rate of aqueous production of 0.32 +/- 0.09 microL/min. Uveoscleral outflow showed an increase of 0.83 +/- 0.23 microL/min. Timolol, applied topically twice daily for one week, reduced the IOP 3.9 +/- 1.0 mm Hg and decreased aqueous flow 0.84 +/- 0.23 microL/min, but produced no change in outflow facility or uveoscleral flow. When epinephrine and timolol are given in combination, the effects in lowering IOP may not be completely additive.