About the Eye
If we think of the eye as a ball, a perfect sphere, what we see when we look at each other is just a fraction of the eye. But behind the eye is at least 90% of that ball that we do not see.
In front of the eye is the cornea, a round, transparent crystal that covers the colored iris and the pupil. The cornea acts as a lens that focuses what we see through the pupil. The pupil opens and closes relating to the amount of light in the environment just like the shutter of a camera. Behind the pupil, there is another lens, this lens also focuses what we see to the retina. The macula is a tiny area in middle of the retina. The macula has millions of light sensing cells that are responsible for the sharp central vision that we use for everyday activities such as reading and driving.
The retina cannot be seen without specialized equipment and dilating the pupil. The retina is a thin membrane that lines the inside of the eye it contains the cells which perceive light and color. Like the film in a camera, it picks up the images that are focused on it and transmits these images via the optic nerve to the brain and the brain translates it so you know what you are seeing. Clear fluid which contains nutrients keeps the eye expanded as a ball. The fluid is constantly being profused into the eye, but it also has to leave, so it leaves through drainage channels in front of the iris.