During the process of accommodation, there is
**Core Concept**
The process of accommodation in the eye involves adjusting the lens shape to focus on objects at varying distances, a function crucial for clear vision. This process is mediated by the ciliary muscles, which regulate the tension on the zonular fibers attached to the lens.
**Why the Correct Answer is Right**
During accommodation, the ciliary muscles contract, reducing the tension on the zonular fibers. This decrease in tension allows the lens to become more spherical, increasing its refractive power and enabling the eye to focus on near objects. The increased curvature of the lens is achieved through the stretching of the lens capsule and the contraction of the lens epithelial cells, which increases the lens's refractive index.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the process of accommodation. While the lens does change shape, it is not due to the contraction of the lens itself, but rather the relaxation of the ciliary muscles.
**Option B:** This option is incorrect because it implies that the lens becomes less curved during accommodation, which is the opposite of what occurs.
**Option C:** This option is incorrect because it does not accurately describe the muscle involved in accommodation. The ciliary muscles, not the extraocular muscles, are responsible for the process of accommodation.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the process of accommodation is a dynamic process that requires the coordinated effort of multiple structures, including the ciliary muscles, zonular fibers, and the lens itself. Understanding the mechanisms behind accommodation is crucial for diagnosing and managing conditions that affect the eye's ability to focus, such as presbyopia.
**Correct Answer:** C.