The lens makes the final focusing effect, to bring light first bent by the cornea, to a sharp image on the retina.

The lens can change focus, so that we can focus on distance then near. The ability to change focus decreases with age, so that by the age of 40 years most adults begin to need reading glasses, (presbyopia).

The focusing power of the lens is changed by changing lens shape: The more spherical the more powerful and the closer things can be read.

The lens is held in a transparent bag (lens capsule). This is suspended from the inside wall of the eye by radial fibers (zonules), connected to the ciliary body. This contains a ring of  muscle which runs around the inside wall. When it contracts the lens power increases.

In later life the lens enlarges, hardens and darkens and develops scratch like opacities due to water splits between the lens fibers. These defects are commonly known as cataract.


Back to Eye Parts

This information site has been provided by varied UK and US eye doctors for patients with eye problems.

Once your eye doctor has made a diagnosis or recommended an investigation or treatment, then you will be able to find further explanation on this site.

It is not a self diagnosis centre. It should not be relied upon without taking professional advice.