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.
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.
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.