- The ciliary muscle to which eye lens is attached and helps to change its focal length by changing radii of curvature of eye lens.
- When the eye is focussed on a distant object, the ciliary muscles are relaxed so that the focal length of eye lens has its maximum value which is equal its distance from the retina.
- When the eye is focussed on a closer object the ciliary muscles are strained and focal length of eye lens decreases. The ciliary muscles adjust the focal length in a such a way that the image is formed on retina.
- This process of adjusting focal length is called accommodation.
- Ciliary muscles are useful to see distant, closer objects clearly.