Final answer:
Pilocarpine is used topically to reduce intraocular pressure in glaucoma and as an injection known as Miostat during eye surgeries to manage pressure.
Step-by-step explanation:
The substance used topically to reduce intraocular pressure (IOP) in glaucoma is pilocarpine. Pilocarpine works as a nonspecific muscarinic agonist that can reverse mydriasis and is administered topically after eye exams. Besides constricting the pupil, pilocarpine's effect on the ciliary muscle contracts and opens perforations at the base of the cornea, which aids in the drainage of aqueous humor from the eye's anterior compartment, thus reducing IOP in glaucoma patients. Pilocarpine, when used intraoperatively, is known by the brand name Miostat and is given via injection into the anterior chamber of the eye to facilitate surgical procedures by managing eye pressure.