What effect does cycloplegia have on the eye's accommodation ability?

Cycloplegia refers to the temporary paralysis of the ciliary muscle of the eye, which is responsible for changing the shape of the lens to focus on objects at varying distances. When cycloplegia occurs, the ciliary muscle is unable to contract, preventing the lens from becoming more rounded for near vision. As a result, the eye loses its ability to accommodate effectively, leading to a state where the eye cannot adjust focus from distant to near objects.

This is particularly useful in certain medical examinations, such as during cycloplegic refraction, where accurate measurement of refractive error is desired without the influence of accommodation. The paralysis allows for a more accurate assessment of a person's prescription for glasses or contact lenses, as it eliminates any potential variability caused by the eye's natural accommodation responses. Therefore, the correct choice reflects the fundamental impact that cycloplegia has on the eye’s ability to change focus between different distances.