Stem cells and the ocular lens : implications for cataract research and therapy

The transparent, avascular and non-innervated ocular lens is suspended in the light path between the cornea and retina by the zonular fibres within the zonula ciliaris (also called the Zonule of Zinn; Fig. 9.1). The lens provides approximately 30% of the eye's focussing power and, through the combined action of the ciliary muscle and zonular fibres, the lens provides all the accommodating ability of the eye, that is, the ability to change focus between near and far objects. These dual properties of transparency and accommodation cause the lens to play a vital role in the development of key motor and social functions that require good vision.