Which of the following is NOT an action of Phenylephrine?

Phenylephrine is a sympathomimetic agent primarily used for its vasoconstrictive properties and its ability to induce pupil dilation (mydriasis) without affecting the ciliary muscle, which leads to its action being distinct from cycloplegic drugs that cause paralysis of this muscle. Therefore, while it facilitates dilation, it does not induce cycloplegia, making cycloplegia an action that Phenylephrine does not perform.

Additionally, Phenylephrine serves as a useful clinical tool in differentiating between conditions like episcleritis and scleritis, where its vasoconstrictive properties may help in evaluating vascular patterns. It can also cause palpebral widening by stimulating the muscle of Müller, enhancing eyelid elevation. Therefore, understanding these pharmacological properties of Phenylephrine clarifies why cycloplegia is not one of its actions.