Retina/Macula/Choroid

The retina acts like the film in a camera to create an image. To do this, the retina, a specialized layer of cells, converts light signals into nerve signals. After light signals are converted into nerve signals, the retina sends these signals to the optic nerve, which carries the signals to the brain. There, the brain helps process the image.
 
The retina is primarily made up of 2 distinct types of cells: rods and cones. Rods are more sensitive to light; therefore, they allow you to see in low light situations but do not allow you to see color. Cones, on the other hand, allow you to see color but require more light.

The macula is located in the central part of the retina. It is the area of the retina that is responsible for giving you sharp central vision. 

The choroid is a layer of tissue that separates the retina and the sclera. It is mostly made up of blood vessels. The choroid helps nourish the retina.