When the light reflected from the object hits the front surface of the eye, the first thing it gets on the cornea is a transparent shield covering the eye in front.

The structure and work of the eye

The cornea focuses the rays entering the eye. After that, the color passes the iris through the hole in its center - the pupil. The pupil - a black spot in the middle of the iris - becomes wider in the dark to let more light into the eye, and turns into a point in bright light.

You can observe the behavior of your pupil by standing in the bathroom in front of the mirror in the dark, and then turning on the light. You will see your pupils narrowing rapidly in the light. The muscles of the iris can stretch or narrow the pupil. The light that has passed through the pupil then passes through the lens - the lens located behind the iris.

The elastic lens of the lens completes the focusing of light rays initiated by the cornea. The lens under the influence of special muscles can change its shape in order to focus the rays emanating from objects that are from the eye at different distances.

A ray of light then penetrates through the dark chamber of the inner cavity of the eye, as the beam of the projector passes through a dark room before illuminating the screen on the opposite wall. A similar screen in the eye is called the retina and consists of 135 million photosensitive cells. More than 95 percent of these cells are sticks; they allow us to see in twilight.The remaining cells are called cones, they function in bright light and provide color vision.

After contact with photons of light, retinal nerve cells send pulses to the brain through the optic nerve. The optic nerve is a kind of emergency exit of the eye. The received impulses are interpreted by the brain, and one picture of the observed object is formed from two images.