Ciliary zonules are a ring of fibrous structures anchoring the ciliary body

with the lens of the eye. These are the structures that help to maintain the position of the lens in the optical path, and anchor muscles that change the shape of the lens to alter focus.

How does the ciliary muscle work?

When the ciliary muscle is contracted, the lens becomes more spherical – and has increased focussing power – due to a lessening of tension on the zonular fibres (a). When the ciliary muscles relax, these fibres become taut – pulling the lens out into a flatter shape, which has less focussing power (b).

What is the process of accommodation?

Accommodation is the process of adjusting the lens of the eye so that you can see both near and far objects clearly. This process is very rapid although changing accommodation from a near object to a far object is faster than going from a far object to a near object (Kirchhof, 1950).