” The lens lies behind the iris and the pupil. It works much like a camera lens. It focuses light onto the retina at the back of the eye, where an image is recorded. The lens also adjusts the eye’s focus, letting us see things clearly both up close and far away. The lens is made of mostly water and protein. Clumps of protein reduce the sharpness of the image reaching the retina. When the protein clumps up, it clouds the lens and reduces the light that reaches the retina. “

Eye Ear Institute