Accommodation is defined as the process by which the crystalline lens varies its focal length in response to changes in the vergence of incident light. Our eyes have been provided with a unique mechanism by which we can even focus the diverging rays coming from a near object on the retina in a bid to see clearly by the mechanism of accommodation. There is no disagreement that a change in the shape of the lens-an increase or decrease in curvature and thickness of its central parts that produces an increase or decrease in the dioptric power of the eye-is the basic mechanism underlying accommodation.