The cornea and lens work together to focus light on the retina. The cornea’s curve refracts the light so it bends inwards while the lens changes shape to bring objects at varying distances into focus.
The cells in the lens are like any other cells: they die and regenerate. Cells reform when they can, but cataracts form when imperfections appear in the new cells. Not unlike scar tissue, cloudy, white, and translucent deposits form where clear, transparent cells used to be, interfering with vision.