Which part of the eye is specifically responsible for focusing light onto the retina?

The lens is the part of the eye that is specifically responsible for focusing light onto the retina. It achieves this by changing shape, a process known as accommodation. When viewing objects at different distances, the lens adjusts its curvature to ensure that light rays are precisely focused on the retina, allowing for clear images to be formed.

The iris plays a role in regulating the amount of light that enters the eye by adjusting the size of the pupil, while the cornea is responsible for a significant portion of the eye's total focusing power, but it does not change shape to focus light on the retina. The pupil, on the other hand, is simply an opening that allows light to enter the eye, but it does not have any focusing capabilities. The combination of these structures works together for vision, but the specific function of focusing light onto the retina is the primary role of the lens.