The ability of eye lens to adjust its focal length to form a sharp image of the object at varying distances on the retina, is called its power of accommodation. Help by the ciliary muscles in accommodation: When we are looking at nearby object, the ciliary muscles contract, it increases the curvature of eye lens. The eye lens then becomes thicker. As a result, the focal length of the eye lens decreases in such a way that a clear sharp image of nearby object is formed on the retina. Thus, the object is seen clearly to us. When we are looking at distant object, these muscles are in relaxed position, the eye lens becomes thinner and the focal length of the eye lens increases. Therefore, the parallel rays coming from the distant object are focussed on the retina and the object is seen clearly to us. Thus, the accommodation power of an eye helps a person to see nearby as well as distant objects clearly.