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Blind spot (vision)

 

 
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Blind spot (vision)
 
 
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A blind spot, also known as a scotoma
Scotoma

A scotoma is an area or island of loss or impairment of visual acuity surrounded by a field of normal or relatively well-preserved Visual perception....
, is an obscuration of the visual field
Visual field

The term 'visual field' is sometimes used as a synonym to field of view, though they do not designate the same thing. The visual field is the "spatial array of visual sensations available to observation in introspection psychological experiments" , while field of view "refers to the physical objects and light sources in the external world...
. A particular blind spot known as the blindspot, or physiological blind spot, or punctum caecum in medical literature is the place in the visual field that corresponds to the lack of light-detecting photoreceptor cells on the optic disc
Optic disc

The optic disc or optic nerve head is the location where ganglion cell axons exit the eye to form the optic nerve. There are no light sensitive photoreceptor to respond to a light stimulus at this point....
 of the retina
Retina

The vertebrate retina is a light sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera....
 where the optic nerve
Optic nerve

The optic nerve, also called cranial nerve II, transmits visual information from the retina to the brain....
 passes through it. Since there are no cells to detect light on the optic disc, a part of the field of vision is not perceived.






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Encyclopedia


A blind spot, also known as a scotoma
Scotoma

A scotoma is an area or island of loss or impairment of visual acuity surrounded by a field of normal or relatively well-preserved Visual perception....
, is an obscuration of the visual field
Visual field

The term 'visual field' is sometimes used as a synonym to field of view, though they do not designate the same thing. The visual field is the "spatial array of visual sensations available to observation in introspection psychological experiments" , while field of view "refers to the physical objects and light sources in the external world...
. A particular blind spot known as the blindspot, or physiological blind spot, or punctum caecum in medical literature is the place in the visual field that corresponds to the lack of light-detecting photoreceptor cells on the optic disc
Optic disc

The optic disc or optic nerve head is the location where ganglion cell axons exit the eye to form the optic nerve. There are no light sensitive photoreceptor to respond to a light stimulus at this point....
 of the retina
Retina

The vertebrate retina is a light sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera....
 where the optic nerve
Optic nerve

The optic nerve, also called cranial nerve II, transmits visual information from the retina to the brain....
 passes through it. Since there are no cells to detect light on the optic disc, a part of the field of vision is not perceived. The brain
Brain

The brain is the center of the nervous system in all vertebrate, and most invertebrate, animals. Some primitive animals such as cnidarian and echinoderm have a decentralized nervous system without a brain, while sponges lack any nervous system at all....
 fills in with surrounding detail and with information from the other eye
Eye

Eyes are Organ that detect light, and send signals along the optic nerve to the visual system and other areas of the brain. Complex optical systems with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system....
, so the blind spot is not normally perceived.

Although all vertebrate
Vertebrate

Vertebrates are members of the subphylum Vertebrata, chordates with Vertebras or Vertebral columns. The grouping sometimes includes the hagfish, which have no vertebrae, but are genetically quite closely related to lampreys, which do have vertebrae....
s have this blind spot, cephalopod
Cephalopod

The cephalopods are the mollusc class Cephalopoda characterized by bilateral symmetry, a prominent head, and a modification of the mollusk foot, a muscular hydrostat, into the form of cephalopod arms or tentacles....
 eyes, which are only superficially similar, do not. In them, the optic nerve approaches the receptors from behind, so it does not create a break in the retina.

The first documented observation of the phenomenon was in the 1660s by Edme Mariotte
Edme Mariotte

Edme Mariotte was a France physicist and priest.Mariotte is best known for his recognition in 1676 of Boyle's Law about the inverse relationship of volume and pressures in gases....
 in France, at the time when it was generally thought that the point at which the optic nerve entered the eye should actually be the most sensitive portion of the retina.

A | align="right" style="font-size: 0.7cm;"| O | style="width: 10cm;" | | align="left" style="font-size: 0.7cm;" | X | |- | colspan="5" height="50px" | |- | colspan="5" style="border:solid 1px #AAAAAA;" | Instructions: You may need to reduce the size of your browser window if your screen is large or at a high resolution. Your face should be very close to the screen. Cover right eye and focus the left eye on the X. Now slowly move away from the screen. The O will disappear, while the A which is further to the left is still visible. (Observe that you do not see a hole. Instead of the O you see a uniform grey background. The "hole" is filled in by your brain. Make sure there is not a glare on the screen as it will obscure the whole vision.)>

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