Which of the following is NOT considered a cycloplegic medication?

Phenylephrine is classified as a sympathomimetic agent primarily used for its vasoconstrictive properties and to dilate the pupil (mydriasis) by stimulating alpha-adrenergic receptors. While it can contribute to the dilation of the pupil, it does not have the ability to paralyze the ciliary muscle, which is a key characteristic of cycloplegic medications.

In contrast, atropine, homatropine, and cyclopentolate all function as anticholinergic agents that inhibit the action of acetylcholine on the muscarinic receptors in the eye. This inhibition leads to both pupil dilation and paralysis of accommodation, which is the hallmark of cycloplegic medications. Therefore, phenylephrine stands apart from these agents as it does not produce the cycloplegic effect.