Loss of acute pilocarpine effect on outflow facility following surgical disinsertion and retrodisplacement of the ciliary muscle from the scleral spur in the cynomolgus monkey.

An ab-interno goniotomy-like operation for disinserting the ciliary muscle from the scleral spur in cynomolgus monkeys is described. Following postoperative miotic and corticosteroid treatment, the eyes did well clinically and the muscle reattached to the sclera posterior to the spur. Outflow facility and intraocular pressure were mildly reduced. There was drainage of aqueous humor via the conventional outflow routes, and blood flow to the ciliary body. The outflow facility increasing effect of intravenous and intracameral pilocarpine was nearly completely eliminated. These and other data suggest that: (1) the ciliary muscle was permanently disconnected, anatomically and functionally, from the trabecular meshwork; (2) the trabecular meshwork and Schlemm's canal remained relatively normal structurally and functionally; (3) monkey eyes with retrodisplaced ciliary muscles may prove valuable for testing the functional effects of drugs directly on the conventional outflow channels, independent of drug actions on the ciliary muscle.