Blind spot (vision)

As a blind spot the location of the visual field is called in ophthalmology, projected onto the papilla of the optic nerve, the ( optic nerve head) in the outer space. Since there are no light receptors on her, she turns for this field region as a " blind spot " is and has an absolute, but physiological visual field defect ( scotoma ) on. The papilla is located anatomically precise approximately 15 ° nose- forward ( nasal) of the fovea centralis, the localization of the blind spot is carried out in the field, however, about 15 ° upward temple ( temporal).

Generally

Normally, the blind spot is not noted, but may be masked by the perceptions of the visual field surrounding areas and especially in the other eye, the blind spot is not at the identical location.

The blind spot exists, since the fibers of the optic nerves attach to the side of the interior of the eye to the visual cells, a piece of escape far extend in the interior of the eye and then bundled together in one place out of the eye - in the papilla. This " inconvenient " at first sight design is explained by the expected development of the human eye in the course of evolution: The retina is formed in ontogeny as a direct protrusion of the brain.

In some other organisms, the eyes are set up differently. Stammen about the light-sensitive cells of the outer tissue layers ( ectoderm ) from those who have eyes (eg, the squid) no blind spot. The fibers of the optic nerve can run from the shielded side of the light receptors quoting directly away from the eye to the brain, without having to first pass through the retina.

Self-experiment

Even more illustrative

Instructions:

The left eye to keep and fix it with the right point. Start with a screen distance of about twice the distance between the black point and the center of the white circle. If you then increase the distance slowly, you can see how the missing part of the pattern is completed, be transmitted even if no " information" about a photoreceptor. The lack of information is completed by the brain. This process is called filling - in.

Discovery

The blind spot was discovered in 1660 by French scientist Edme Mariotte. He presented his discovery to the French court by similarly the tests above, a small coin seemingly magically to the " disappearance " did a test.