Final answer:
Cycloplegic and mydriatic medications are administered during eye exams to dilate the pupil for a thorough internal examination and to temporarily paralyze focusing muscles to measure refractive errors; pilocarpine can counteract mydriasis and treat glaucoma.
Step-by-step explanation:
Cycloplegic and mydriatic medications are often administered during an eye examination in an ophthalmologist's or optometrist's office. Mydriatic agents, like phenylephrine, are used to dilate the pupil (a process known as mydriasis) to allow a better view of the interior structures of the eye.
Cycloplegic drugs, which also dilate the pupil, temporarily paralyze the ciliary muscle, making it impossible for the eye to focus, thus facilitating the accurate measurement of refractive errors. On the other hand, pilocarpine is a muscarinic agonist that can reverse mydriasis by constricting the pupil and is used to treat glaucoma by facilitating the drainage of aqueous humor from the anterior compartment of the eye, thereby reducing intraocular pressure.