What type of eye drop dilates the pupil without causing cycloplegia?

The correct answer is mydriatic, as mydriatic eye drops are specifically designed to dilate the pupil (mydriasis) without affecting the ciliary muscle, which is responsible for accommodating and focusing. This means that mydriatics can enlarge the pupil while allowing the eye to maintain its ability to focus on objects at various distances.

In contrast, cycloplegic drops are used to not only dilate the pupil but also paralyze the ciliary muscle, resulting in loss of accommodation. This can be useful for certain examinations and treatments, but it does not provide the desired effect when only dilation is needed. Antihistamines are primarily used to treat allergic reactions and symptoms such as itching and watery eyes, not for pupil dilation. The term dilating drop is a general term that can encompass both mydriatics and cycloplegics, but it doesn't specify the absence of accommodation paralysis, which is a key factor in this scenario.