Close the left eye with the palm and look at this picture right eye. Focus in this look at the black cross.
Illustration by MARRIOTT for detection of the blind spot of the eye
If you will be closer to the figure or to move away from him, then one day you will find that black circle... was gone!
Why is this happening? Because the circle hit the sector of so-called blind spot of the eye.
The retina is arranged not evenly. In the center of the fundus there is a small recess of the Central hole. This place is the best vision. The main line of sight is always directed along the axis of the Central hole center of the lens is considered the subject:
Around the Central fossa is located in the yellow spot. This place daylight vision and the best color perception. The farther away from the yellow spot, the smaller the cone contains the retina and more sticks. Cones are adapted for color vision, and sticks - for twilight vision for perception of form.
At some distance from the yellow spot is the so-called blind spot. There are no cones or sticks, this place eye does not see. This place is situated nipple optic nerve (on the picture above blind spot marked in blue).
Why blind spot? Could all optic nerve fibers going to the cones and rods, to collect somewhere in the back of the eye, and not on the surface of the retina? And why blind spot is here, and not somewhere in the future because of the space in the eyeball is still a lot?
In accordance with its eye structure is not simply transmits to the brain the light signals received by him from the outside, not the mirror reflects all that is before him, and prepares information for the brain in a certain order and subordination. The Central fossa and the macula give the most clear image and better color perception. The peripheral part of the clear field of view gives a less clear perception and thereby provides the dominant role of the center. Blind spot is not involved in visual perception at all. For the blind spot is even more distant periphery, which provides only a General perception of being as a kind of background for a clear field of view, but it is very sensitive to light signals from moving objects that biologically it makes sense and is very important in the struggle for existence.
What makes outermost periphery of the eyeball where light rays do not fall? There is created a null color. He serves as the basis for comparison of all color sensations, which gives the retina.