Which structure is responsible for controlling accommodation of the eye?

The ciliary body is the structure responsible for controlling accommodation in the eye. Accommodation refers to the process by which the eye adjusts its focus for near and distant objects. This adjustment is made possible through the action of the ciliary muscles, which are part of the ciliary body. When these muscles contract, they reduce tension on the zonules (the fibers that hold the lens in place) and allow the lens to become more rounded. This increased curvature of the lens enhances its ability to refract light for closer vision. Conversely, when the ciliary muscles relax, the tension on the zonules increases, flattening the lens for distant vision.

While the lens and cornea do play significant roles in focusing light, they do not have the muscular control required for adjusting focus. The cornea serves primarily as a fixed optical element, while the lens adjusts its shape based on the actions of the ciliary body. The fovea is involved in high-acuity vision but does not participate directly in the accommodation process. Thus, the ciliary body is crucial for the dynamic adjustment of the lens to facilitate clear vision at various distances.