How the Eye Works
The eye works like a camera. As light travels through the cornea and lens it is focused on to the retina at the back of the eye. The retina then converts the image to an electrical signal and sends it to the brain for processing.
As we brings things closer to the eye the image would naturally go blurry if the eye couldn’t change focus. The lens in the eye is attached to muscles which pull on the lens as things get closer enabling us to see clearly up close.