The crystalline lens is a refractile and biconvex structure that is important for refracting light rays and focussing them onto the retina. Developmentally it originates from the ingrowth of the surface ectoderm which forms the lens placode. Therefore the lens is encapsulated in a layer of epithelial cells which continue to divide and migrate forming lens fibres that are arranged in compact Y-shaped fibres that progressively get compacted into the lens core with an ability to change its shape and refractive power. Disorders in development may lead to abnormalities in lens shape, clarity and position. The ageing process of the human body leads to progressive opacification of the lens and loss of clarity of vision. Local pathology such as inflammation and trauma may cause damage to the structure and arrangement of lens fibres. Similarly systemic disorders and errors of metabolism may lead to opacification of the lens leading to cataracts which is a common cause of visual disability.