Which part of the eye is primarily involved in focusing light?

The lens of the eye is primarily responsible for focusing light. It is a transparent, flexible structure located behind the iris and the pupil. The lens adjusts its shape to change the focal distance of the eye, allowing it to focus on objects at various distances. This process is called accommodation. When viewing distant objects, the lens becomes flatter, and when looking at closer objects, it becomes thicker and more curved. This ability to change shape is crucial for clear vision, as it helps direct light precisely onto the retina, where the image is processed.

While the cornea does contribute to the eye's focusing ability, it mainly provides the majority of the eye's optical power. The sclera, the white outer layer of the eye, does not participate in focusing light; rather, it provides structural support. The ciliary body plays a supporting role in changing the shape of the lens through the contraction of the ciliary muscles, but it's the lens itself that is responsible for the majority of light refraction necessary for focusing images on the retina.