Parasympathomimetics in glaucoma
Parasympathomimetics such as pilocarpine stimulate the drainage of aqueous humour by increasing the uveoscleral outflow. Pilocarpine is a direct acting cholinomimetic with a short duration of action. It activates muscarinic receptors in the ciliary muscle, which improves uveoscleral outflow.
Secondly, pilacarpine activates muscarinic receptors on the iris and ciliary body, causing pupil constriction. Due to this motic action, an obvious adverse effect is a permanently constricted pupil. Long-term treatment can cause permanent accommodative spasm and give rise to symptoms like blurred vision and headache.