Accommodation of the eye

The eye focuses light from objects at different distances onto the retina, the light-sensitive layer at the back of the eye. To do this, it changes the shape of its lens. This adjustment is called accommodation.

The shape of the lens determines how strongly it refracts, or bends, light. A thicker, more curved lens refracts light more strongly than a thinner, less curved lens. The ciliary muscles and suspensory ligaments change the lens shape by altering the tension on it.

Focusing on a near object

The ciliary muscles contract, reducing tension in the suspensory ligaments. The lens becomes thicker and more curved, so it refracts light more strongly. This brings light from the near object into focus on the retina.

Focusing on a distant object

The ciliary muscles relax, making the suspensory ligaments taut. The ligaments pull the lens thinner and less curved, so it refracts light less strongly. This brings light from the distant object into focus on the retina.