The ability of the eye lens to change its focal length is known as the power of accommodation. The ciliary muscles present in the eye change the curvature of the lens which in turn change the focal length of the lens. To see nearby objects clearly, the focal length of lens should be less than that for seeing objects at normal distance. The ciliary muscles contract and cause the lens to become thicker. A thicker lens will have a decreased focal length than a normal sized lens so nearby objects will be visible.
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