[The mechanism of cholinergic effects on lowering intraocular pressure]

The relationship between vasomotoric activity and blood vessel permeability was studied in the course of discovering the ocular hypotonising mechanism of cholinergic drug activity (pilocarpin and carbamylcholin). The authors found, in experimental conditions, that the vasomotoric activity (vasodilatation) of the two cholinergic drugs is expressed in the increased permeability of the blood-aqueour barrier. In the presence of an elevated extracirculatory pressure (IOP), as in glaucoma, vasodilatation under the influence of cholinergic drugs, is converted to passive vasoconstriction which leads to reduced aqueous humor production. Carbamilcholin reduces aqueous humor production in a greater extent than pilocarpin.