Norepinephrine (4%) as free base produced a significant fall in intraocular pressure and resistance to outflow. This effect was sustained for up to 20 weeks. No significant difference could be shown between the effect of 2%, 3%, and 4% norepinephrine on the aqueous humor dynamics. The effect on pressure and facility was shown in eyes with ocular hypertension and with glaucoma.
An additive effect was observed after use of norepinephrine with pilocarpine in the treatment of glaucoma. Crossover studies between epinephrine borate 1% and norepinephrine borate 4% revealed no significant difference. Like epinephrine, norepinephrine produces a conjunctival hyperemia in many patients. However, there is an absence of tachycardia after use of norepinephrine, and one person in this study showed an allergic reaction to epinephrine that cleared promptly and completely when norepinephrine was substituted.
Pollack IP, Rossi H. Norepinephrine in Treatment of Ocular Hypertension and Glaucoma. Arch Ophthalmol. 1975;93(3):173-177. doi:10.1001/archopht.1975.01010020181002