Structure of the eye
A cross-section view of the eye is shown in the diagramme. The optical system forms an image of the object being viewed on the retina, where photosensitive cells convert it into nerve signals that pass to the brain. As a result, the visual sensation is effectively processed by the visual cortex of the brain. The optical system consists of the cornea, iris, lens and vitreous body that regulate the amount of light and the sharpness of the image formed on the retina. There are two types of photosensitive cells on the retina that respond to light by generating neural impulses.
When viewed from the direction in which light enters the eye, the first retina layer consists of optic nerves. Underneath there is tissue that converts the input from the photosensitive cell into neural impulses, and cone and rod cells are at the bottom. The tissue covering the photosensitive cells is transparent.