The term 'PUPIL's Neighbor' refers to the four parts of the eye that surround the PUPIL. The RETINA is a thin layer of tissue at the back of the eye that contains light-sensitive cells and is responsible for converting light into electrical signals that are sent to the brain. The LENS is a transparent structure located behind the IRIS that helps focus light onto the RETINA. The IRIS is the colored part of the eye that controls the amount of light entering the eye. Finally, the cornea is the transparent outer layer of the eye that helps focus light onto the LENS. Together, these four parts of the eye form the PUPIL's neighbors and are essential for vision.