Final answer:
In acute angle-closure glaucoma, pilocarpine, a muscarinic agonist, is used to facilitate the iris muscle's response to miotics, helping to reduce intraocular pressure by allowing drainage of aqueous humor. Phenylephrine, which causes mydriasis, and muscarinic antagonists like atropine and scopolamine play a role but are more hazardous due to their toxicity and broader autonomic effects.
Step-by-step explanation:
In cases of acute angle-closure glaucoma, drugs like pilocarpine are used to facilitate the response of the iris muscle to miotics. Pilocarpine is a muscarinic agonist that causes the pupil to constrict by acting on the iris and also induces contraction of the ciliary muscle. This action helps open up the perforations at the base of the cornea, enabling the drainage of aqueous humor from the anterior compartment of the eye and thus, reducing intraocular pressure associated with glaucoma.On the other hand, phenylephrine, an agent that causes mydriasis by mimicking the action of norepinephrine, is used during eye exams to dilate the pupil. However, miotics like pilocarpine are needed to reverse this dilation in acute angle-closure glaucoma. Additionally, muscarinic antagonists such as atropine and scopolamine, derived from plants like belladonna, can also be involved, but their usage is more complex due to their potential toxicity and broader effects on the parasympathetic nervous system.