The lens is a clear and flexible structure located behind the iris. Its main function is to focus light onto the fovea, enabling us to see in sharp detail.

This is a three dimensional illustration of the eye. The structures are listed from front to back. The outermost structure is the cornea, followed by the sclera, pupil, iris, lens, retina, macula, optic disc and the optic nerve.
Location of the lens in relation to other structures

Ciliary body

The lens is supported by ligaments called the lens zonules, which are anchored to muscles of the ciliary body, a ring-like tissue encircling the lens. The contraction or relaxation of the ciliary muscles enables the lens to change its shape to focus on objects at various distances. 

Diagrams showing the inside workings of the eye. When focusing at a distant object, the ciliary body tightens, elongating the lens. When focusing at a near object, the ciliary body relaxes and the lens becomes shorter and thicker.
The action of the ciliary muscle changes the shape of the lens to focus on objects at different distances

In addition to providing structural support to the lens, the ciliary body also secretes a type of fluid called the aqueous humour.  This fluid provides nourishment to cells inside the eye and also to keep the eyeball inflated.


Cataract is the clouding of the lens leading to blurred or misty vision. There are many causes to cataract formation but the most common by far is ageing. In many inherited eye disorders, cataracts might be present from birth or develop at a younger age than people not affected by these disorders. Cataracts that are present form birth are referred as congenital cataracts.  

There is significant cloudiness of the lens
A short animation explaining about cataracts