A blind spot is a light-insensitive area on the retina. This is quite normal for the eyes of a healthy person. There is a blind spot due to the peculiar structure of the eyeball. In this area, the nerve fibers go on top of the retina, they collect in the optic nerve, and that, in turn, passes through the retina to the other side. This area of the eye does not contain light receptors and, accordingly, does not perceive visual information.
This irrational structure of the eye has an explanation in terms of evolution. Cephalopods do not have any blind spots in their eyes. In octopuses, for example, nerve fibers form in the optic nerve on the other side of the retina. Some try to give this phenomenon a rational explanation and evaluate it from the point of view of natural “energy saving” and more rational use of the photopigment resource.
Blind spots are present in each eye and have the property to be arranged symmetrically. A person practically does not notice their presence. In order to identify a blind spot in the eye, you must use a special test picture. In addition, the work of the brain allows you to adjust the image perceived by the organs of vision, as a result we see a holistic image of the object without interference and spots.
Thus, the device of the eye and the features of the central nervous system allow a person to focus on considering the subject that interests him. Either interest is dictated by vital necessity, or is caused by the exceptional beauty of forms, in any case, a healthy eye allows you to get all the necessary visual information.
If we examine in more detail the structure of the human eye, we can identify a small depression located in the center of the fundus, it is also called the central fossa. This place is the center of the best perception of the "picture". Correspondingly to the main line of sight, the axis is directed along the central fossa, the center of the lens and the subject in question.
The area around the central fossa has become the location of the macula. This place is responsible for daytime vision and the best color perception. Removing from a macula leads to a reduction in the number of cones in the retina and an increase in the content of rods. It is the sticks that are responsible for twilight vision and serve as a means of best perception of forms. It is precisely near the macula that the blind spot is located. As mentioned earlier, this site is free from cones and rods. The glade for the optic nipple does not see anything.
The arrangement of the eyes is extremely reasonable. This natural optical device has high functionality and is capable of providing up to ninety percent of the information entering the human brain.
In fact, the presence of a light spot is the only natural irrationality in the structure of the human eye, which is fully compensated by its multifunctionality. If the central fossa and the yellow spot are responsible for the sharpness of the image and the best perception of light, then the peripheral part of the field, the so-called clear vision, has the function of creating the background and ensuring the central role of the center. Then follows the more distant periphery, it is responsible for the general perception and has an increased sensitivity to motion signals. And the farthest periphery, on which the rays of light do not even fall, creates a basic zero-color. It is the starting point for comparing color sensations.
For the first time, a blind spot in 1668 was described by Marriott Edm. For the king of France, Louis XIV, this discovery became a kind of entertainment. He had unhealthy pleasure in treating his subjects as if they were headless. In modern literature, it was not without the use of the image of this physiological feature of the structure of the human eye. The book "Stalker. Blind spot ”by Victor Nochkin is a vivid example of this.