Final answer:
The lens is a transparent, curved structure in the eye that focuses light onto the retina, designed to adjust focus for objects at different distances.
Step-by-step explanation:
The structure being described is the lens of the eye, which is a curved, transparent structure that provides additional focus for light entering the eye. This lens is capable of changing its shape thanks to the muscles it is attached to, allowing for the adjustment of focus on objects at varying distances. Light that enters the eye and passes through the lens is focused on the retina, particularly on a region called the fovea, which contains densely packed cones responsible for sharp central vision and color perception.