Explain about the term accommodation.

Normally, the human eye focuses at objects at infinity, without exerting any power. This implies that while a person is observing an object at infinity, the eye is at rest and no effort is needed to focus on the object. If the object moves closer from infinity, till a distance of 6 meters from the eye, still no additional power or effort is required to be able to focus on the object. However when an object moves closer than 6 meters, the light rays entering the eye from the objects is more divergent. So as to bring these divergent light rays into focus over the retina the diopteric power of the eye must be increased. The mechanism by which the eye increases its diopteric power and hence the ability to focus at an object close to 154 the eye is called Accommodation.

Ray of light focussed behind the retina (dotted line) before accommodation, and on the retina (solid line) with the help of accommodation