When the ciliary muscle is relaxed the suspensory ligament is taut and the tautness pulls on the edges of the lens and makes it flatter and less convex.
As a result the change in lens shape allows the eye to focus on distant objects.
What happens to the lens when the ciliary muscles contract is the lens becomes more spherical and has increased focusing power due to a lessening of tension on your zonular fibers.
When your ciliary muscles relax, the fibers become taut and pulls the lens out into a flatter shape, which has less focusing power.
The ciliary muscles pull on the suspensory ligaments "zonules" which hold the lens in place and this contraction causes the lens to become more spherical and increases the curvature.
The contraction of the ciliary muscles also cause the center of the lens to thicken and this further increases the lenses focusing power.
The situation that results in the lens of the eye having a more rounded shape is the contraction of your ciliary muscles that relax the suspensory ligaments which support the lens and allow it to become more spherical and increase it's refractive power.
This process is called accommodation and the eye lens becomes more rounded and thicker when focusing on near objects.
Astigmatism also makes the shape of your eye more curved that it should be and causes blurred vision at all distances.
And in a condition called keratoconus, the cornea thins and then gradually bulges outwards into a cone shape and can also cause blurry and distorted vision.
The shape of your eye lens changes as a result of the contraction and relaxation of the ciliary muscles.
The ciliary muscles are attached to your suspenzory zonules which in turn connect to the eye lens.
And when the ciliary muscles contract, the zonules relax and allow the lens of the eye to become more rounded and increase it's refractive power.
And when the ciliary muscles relax, the zonules tighten, pulling the lens of the eye flatter and decreases it's refractive power.
The process is called accommodation and allows your eye to focus on objects at different distances.