Anterior segment chemical sympathectomy by 6-hydroxy-dopamine. I. Effect on intraocular pressure and facility of outflow.

Histoflnorometric techniques have confirmed that topical ocular application of 6-hydroxydopamine, a norepinephrine congener, causes a selective and reversible destruction of syynpathetic nerve terminals in the anterior segment. An investigation of the effects of "chemical sympatheclomy" on the pupil, intraocular pressure, and facility of outflow showed: the pupil underwent a sequence of changes characteristic of surgical sympathetic denervation, but with a different time course; the intraocular pressure .was significantly lowered, transiently in rabbits and of longer duration in monkeys; the facility of outflow was transiently increased in monkeys and probably in rabbits; the episcleral venous pressure was unchanged in both species. It was concluded that the lowered intraocular pressure and lowered outflow pressure were the result of a reduction of aqueous inflow. There was no unequivocal experimental demonstration of supersensitization to topical norepinephrine or isoproterenol following chemical sympathetic denervation; however, the experiments were not conclusive on this important point. It was concluded that chemical sympathectomy with 6-hydroxy-dopamine reproduces many of the ocular phenomena of surgical sympathectomy. 6-Hydroxy-dopamine is a useful drug for experimental ophthalmology, and may be useful clinically.