Which of the following effects is associated with cholinergic agonists in the eyes?

Cholinergic agonists are medications that stimulate the parasympathetic nervous system by activating acetylcholine receptors. In the context of the eyes, these agents primarily act on the muscarinic receptors located in the iris sphincter muscle, leading to the constriction of the pupil, a phenomenon known as miosis.

When cholinergic agonists induce miosis, they contract the circular muscles of the iris, resulting in a smaller pupil size. This effect is beneficial in the treatment of conditions like glaucoma, as it also facilitates the drainage of aqueous humor, thereby reducing intraocular pressure.

In contrast, increased intraocular pressure is generally associated with conditions like glaucoma and is not a desired effect of cholinergic agonists. Mydriasis, or pupil dilation, is typically caused by antagonists that block the actions of acetylcholine at the muscarinic receptors. Blurred vision can occur as a result of some ophthalmic agents but is not a direct effect of cholinergic agonists in the context of their action on pupil size. Thus, miosis is recognized as the characteristic effect of cholinergic agonists in the eyes, making it the correct answer in this scenario.