Final answer:
True, agents that mimic the sympathetic nervous system, such as phenylephrine, cause pupillary dilation, while cycloplegic agents paralyze ciliary muscles for diagnostic purposes.
Step-by-step explanation:
The statement that agents mimicking the sympathetic nervous system result in pupillary dilation is true. Compounds like phenylephrine mimic the action of norepinephrine by binding to adrenergic receptors in the radial fibers of the iris smooth muscle, leading to dilation of the pupil, a condition known as mydriasis. On the other hand, cycloplegic agents induce paralysis of the ciliary muscles, which is used in diagnostic testing to prevent the accommodation of the lens and to allow for a thorough examination of the eye. One such agent is pilocarpine, which is a muscarinic agonist that causes the ciliary muscle to contract, thus helping to reduce intraocular pressure in conditions like glaucoma.