The lens in the eye responsible for focusing light is called the crystalline lens. This flexible structure changes shape, controlled by the ciliary muscles, allowing the eye to focus on objects at varying distances, a process known as accommodation. The lens works in conjunction with the cornea to refract light rays and create a clear image on the retina. It is vital for vision, and any impairment can lead to conditions such as myopia or hyperopia, affecting the clarity of sight.