|
This article or section does not cite its references or sources.
You can help Wikipedia by introducing appropriate citations. Binocular vision is vision in which both eyes are used together. The word binocular comes from two Latin roots, bin for two, and oculus for eye. Having two eyes confers at least four advantages over having one. First, it gives a creature a spare eye in case one is damaged. Second, it gives a wider field of view. For example, a human has a horizontal field of view with one eye of about 150 degrees and with two eyes of about 180 degrees. Third, it gives binocular summation in which the ability to detect faint objects is enhanced. Fourth it can give stereopsis in which parallax provided by the two eyes' different positions on the head give precise depth perception. Such binocular vision is usually accompanied by singleness of vision or binocular fusion, in which a single image is seen despite each eye's having its own image of any object. This article or section does not cite its references or sources. ...
The human eye. ...
Latin is an ancient Indo-European language originally spoken in Latium, the region immediately surrounding Rome. ...
The field of view is the part of the observable world that is seen at any given moment. ...
It has been suggested that Stereoscopic vision be merged into this article or section. ...
This article or section does not cite its references or sources. ...
Depth perception is the visual ability to perceive the world in three dimensions. ...
Other phenomena of binocular vision include utrocular discrimination, eye dominance, allelotropia, and binocular rivalry. It has been suggested that this article or section be merged into laterality. ...
Binocular rivalry is a phenomenon of visual perception in which perception alternates between different images presented to each eye. ...
Some animals, usually prey animals, have their two eyes positioned on opposite sides of their heads to give the widest possible field of view. In such animals, the eyes often move independently to increase the field of view. Even without moving their eyes, some birds have a 360-degree field of view. The field of view is the part of the observable world that is seen at any given moment. ...
Eye movements are the voluntary or involuntary movements of the eye. ...
Prey can refer to: Look up Prey in Wiktionary, the free dictionary A prey animal eaten by a predator in an act called predation. ...
Other animals, usually predatory animals, have their two eyes positioned on the front of their heads, thereby reducing field of view in favour of stereopsis. In such animals, the eyes usually move together. When the eyes move laterally, in the same direction, this is called a version. When the eyes move in opposite directions, to an object closer than where the eyes are pointing or farther than where the eyes are pointing, this is called a vergence. When the eyes move in, it is a convergence eye movement; when the eyes move out, it is a divergence eye movement. This snapping turtle is trying to make a meal of a Canada goose, but the goose is too wary. ...
It has been suggested that Stereoscopic vision be merged into this article or section. ...
A vergence is the simultaneous movement of both eyes in opposite directions to obtain or maintain single binocular vision ^ . The two eyes converge to point to the same object When a creature with binocular vision looks at an object, the eyes must rotate around a vertical axis so that the...
In the absence of a more specific context, convergence denotes the approach toward a definite value, as time goes on; or to a definite point, a common view or opinion, or toward a fixed or equilibrium state. ...
In vector calculus, the divergence is an operator that measures a vector fields tendency to originate from or converge upon a given point. ...
Some animals (including some humans, notably exotropes) use both of the above strategies. A starling, for example, has laterally placed eyes to cover a wide field of view, but can also move them together to point to the front so their fields overlap giving stereopsis. A remarkable example is the chameleon, whose eyes appear to be mounted on turrets, each moving independently of the other, up or down, left or right. Nevertheless, the chameleon can bring both of its eyes to bear on a single object when it is hunting, showing vergence and stereopsis. Genera Aplonis Mino Basilornis Sarcops Streptocitta Enodes Scissirostrum Sarroglossa Ampeliceps Gracula Acridotheres Leucopsar Sturnia Sturnus Creatophora Fregilupus (extinct) Necropsar (extinct) Coccycolius Lamprotornis Cinnyricinclus Spreo Cosmoparus Onychognathus Poeoptera Grafisia Speculipastor Neochicla Buphagus See also: Myna, Oxpecker Starlings are small to medium-sized passerine birds in the family Sturnidae. ...
Genera Bradypodion Calumma Chamaeleo Furcifer Brookesia Rhampholeon Chameleons (family Chamaeleonidae) are squamates that belong to one of the best-known lizard families. ...
Turret (highlighted) attached to a tower on a baronial building in Scotland In architecture, a turret is a small tower that projects from the wall of a building, such as a medieval castle or baronial house. ...
Binocular summation Binocular summation means that the detection threshold for a stimulus is lower with two eyes than with one. There are two forms. First, when trying to detect a faint signal, there is a statistical advantage of using two detectors over using one. Mathematically, the advantage is equal to the square root of 2, about 1.41. Second, when some cells in the visual cortex receive input from both eyes simultaneously, they show binocular facilitation, a greater level of activity than the sum of the two activities evoked separately from each eye. Any advantage in using two eyes in detection task over 1.41 is credited to this sort of mechanism, dubbed neural summation. Look up Threshold in Wiktionary, the free dictionary. ...
In physiology, a stimulus is a detectable change in the internal or external environment. ...
Visual cortex is the term applied to both the primary visual cortex (also known as striate cortex or V1) and upstream visual cortical areas also known as extrastriate cortical areas (V2, V3, V4, V5). ...
Binocular interaction Apart from binocular summation, the two eyes can influence each other in at least three ways. - Pupillary diameter. Light falling in one eye affects the diameter of the pupils in both eyes. One can easily see this by looking at a friend's eye while he or she closes the other: when the other eye is open, the pupil of the first eye is small; when the other eye is closed, the pupil of the first eye is large.
- Accommodation and vergence. Accommodation is the state of focus of the eye. If one eye is open and the other closed, and one focusses on something close, the accommodation of the closed eye will become the same as that of the open eye. Moreover, the closed eye will tend to converge to point at the object. Accommodation and convergence are linked by a reflex, so that one evokes the other.
- Interocular transfer. The state of adaptation of one eye can have a small effect on the state of light adaptation of the other. Aftereffects induced through one eye can be measured through the other.
The human eye The pupil is the central transparent area (showing as black). ...
The human eye The pupil is the central transparent area (showing as black). ...
Light from a single point of a distant object and light from a single point of a near object being brought to a focus by changing the curvature of the lens. ...
A vergence is the simultaneous movement of both eyes in opposite directions to obtain or maintain single binocular vision ^ . The two eyes converge to point to the same object When a creature with binocular vision looks at an object, the eyes must rotate around a vertical axis so that the...
The eye is an adaptation. ...
Utrocular discrimination Utrocular discrimination is the ability to tell, when both eyes are open, to which eye a monocular stimulus was shown.
Singleness of vision Once the fields of view overlap, there is a potential for confusion between the left and right eye's image of the same object. This can be dealt with in two ways: one image can be suppressed, so that only the other is seen, or the two images can be fused. If two images of a single object are seen, this is known as double vision or diplopia. Fusion of the images from the two eyes is considered to be separate from stereopsis for at least two reasons. First, some disorders of binocular vision, such as strabismus can spare fusion but abolish stereopsis. Second, the depth of an object either much nearer to or farther from where the eyes are fixating can be accurately judged despite the images of the object appearing double. Censorship is the control of speech and other forms of human expression, often by government intervention. ...
Double vision may refer to: Diplopia, the perception of two images from a single object. ...
Diplopia, commonly known as double vision, is the perception of two images from a single object. ...
It has been suggested that Stereoscopic vision be merged into this article or section. ...
For the protein Strabismus, see Strabismus (protein) Strabismus, also known as heterotropia, squint, crossed eye, cockeyed, wandering eye, or wall eyed, is a condition in which the eyes are not properly aligned with each other. ...
Fusion of images occurs only in a small volume of visual space around where the eyes are fixating. Running through the fixation point in the horizontal plane is a curved line for which objects there fall on corresponding retinal points in the two eyes. This line is called the empirical horizontal horopter. There is also an empirical vertical horopter, which is effectively tilted away from the eyes above the fixation point and towards the eyes below the fixation point. The horizontal and vertical horopters mark the centre of the volume of singleness of vision. Within this thin, curved volume, objects nearer and farther than the horopters are seen as single. The volume is known as Panum's fusional area (it's presumably called an area because it was measured by Panum only in the horizontal plane). Outside of Panum's fusional area (volume), double vision occurs. The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ...
When each eye has its own image of objects, it becomes impossible to align images outside of Panum's fusional area with an image inside the area. This happens when one has to point to a distant object with one's finger. When one looks at one's fingertip, it is single but there are two images of the distant object. When one looks at the distant object it is single but there are two images of one's fingertip. To point successfully, one of the double images has to take precedence and one be ignored or suppressed. The eye of the image that takes precedence is called the dominant eye. Eye dominance (sometimes called eyedness) refers to the tendency to use one eye more than the other in certain tasks involving precise hand-eye coordination and a reasonably distant target. ...
Stereopsis Stereopsis is an ability to make fine depth discriminations from parallax provided by the two eye's different positions on the head. There are two sorts: quantitative stereopsis, in which the depth seen is very similar to the actual depth of the object being judged, and qualitative stereopsis, in which the depth is correctly nearer or farther than the fixation point but the amount of depth does not grow with distance of the object from the fixation point. Quantitative stereopsis holds for small distances from the fixation plane (approximately within Panum's fusional area); qualitative stereopsis holds for larger distances from the fixation plane (outside of Panum's fusional area). Eventually an object can be moved so far from the fixation plane that there is no sense of depth of the double images--instead they appear to be on the fixation plane. It has been suggested that Stereoscopic vision be merged into this article or section. ...
This article or section does not cite its references or sources. ...
Allelotropia Because the eyes are in different positions on the head, any object away from fixation and off the plane of the horopter has a different visual direction in each eye. Yet when the two monocular images of the object are fused, the object has a new visual direction, essentially the average of the two monocular visual directions. This is called allelotropia. The origin of the new visual direction is a point approximately between the two eyes, the so-called cyclopean eye. The position of the cyclopean eye is not usually exactly centred between the eyes, but tends to be closer to the dominant eye.
Binocular rivalry When very different images are shown to the same retinal regions of the two eyes, perception settles on one for a few moments, then the other, then the first, and so on, for as long as one cares to look. This alternation of perception between the images of the two eyes is called binocular rivalry. Binocular rivalry is a phenomenon of visual perception in which perception alternates between different images presented to each eye. ...
Disorders of binocular vision To maintain stereopsis and singleness of vision, the eyes need to be pointed accurately. The position of each eye in its orbit is controlled by six extraocular muscles. Slight differences in the length or insertion position or strength of the same muscles in the two eyes can lead to a tendency for one eye to drift to a different position in its orbit from the other, especially when one is tired. This is known as phoria. One way to reveal it is with the cover-uncover test. To do this test, look at a cooperative person's eyes. Cover one eye of that person with a card. Have the person look at your finger tip. Move the finger around; this is to break the reflex that normally holds a covered eye in the correct vergence position. Hold your finger steady and then uncover the person's eye. Look at the uncovered eye. You may see it flick quickly from being wall-eyed or cross-eyed to its correct position. If the uncovered eye moved from out to in, the person has exophoria. If it moved from in to out, the person has esophoria. If the eye did not move at all, the person has orthophoria. Most people have some amount of exophoria or esophoria; it is quite normal. If the uncovered eye also moved vertically, the person has hyperphoria (if the eye moved from up to down) or hypophoria (if the eye moved from down to up). Such vertical phorias are quite rare. It is also possible for the covered eye to rotate in its orbit. Such cyclophorias cannot be seen with the cover-uncover test; they are rarer than vertical phorias. In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ...
The extraocular muscles are the six muscles that control the movements of the eye. ...
During the cover-uncover test, a person with some phoria will notice a brief episode of double vision or diplopia after uncovering the eye. This is a normal consequence of the eye's being briefly misaligned. If the diplopia is enduring, that is considered a disorder. Diplopia, commonly known as double vision, is the perception of two images from a single object. ...
The cover-uncover test can also be used for more problematic disorders of binocular vision, the tropias. In the cover part of the test, the examiner looks at the first eye as he or she covers the second. If the eye moves from out to in, the person has exotropia. If it moved from in to out, the person has esotropia. People with exotropia or esotropia are wall-eyed or cross-eyed respectively. These are forms of strabismus with amblyopia. When the covered eye is the non-amblyopic eye, the amblyopic eye suddenly becomes the person's only means of seeing. The strabismus is revealed by the movement of that eye to fixate on the examiner's finger. There are also vertical tropias (hypertropia and hypotropia) and cyclotropias. Exotropia is a form of strabismus where the eyes are deviated outward. ...
Person exhibiting esotropia of the right eye Esotropia is a form of strabismus where one or both of the eyes turn inward (often called lazy eye). The most common type of esotropia occurs in approximately one to two percent of the population. ...
For the protein Strabismus, see Strabismus (protein) Strabismus, also known as heterotropia, squint, crossed eye, cockeyed, wandering eye, or wall eyed, is a condition in which the eyes are not properly aligned with each other. ...
Amblyopia, or lazy eye, is a disorder of the eye. ...
Hypertropia is a condition of misalignment of the eyes (strabismus), whereby the visual axis of one eye is higher than the fellow fixating eye. ...
Hypertropia is a condition of misalignment of the eyes (strabismus), whereby the visual axis of one eye is higher than the fellow fixating eye. ...
Rembrandt as a person without binocular vision People whose eyes failed to align correctly could have no binocular vision. However, to an artist, this disability could have been a gift.
In an article published on September 16, 2004 in The New England Journal of Medicine, Margaret S. Livingstone, professor of neurobiology of Harvard Medical School, suggested that Rembrandt, generally considered one of the greatest painters in European art history, suffered from this disability. She made this conclusion after having studied 36 of Rembrandt's self-portraits. September 16 is the 259th day of the year (260th in leap years). ...
2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ...
The New England Journal of Medicine (NEJM) is a peer-reviewed medical journal published by the Massachusetts Medical Society with the highest impact factor for a general medical journal. ...
Neurobiology is a branch of biology that is involved in the study of nervous systems of all animals from a biological and evolutionary perspective. ...
Shield of Harvard Medical School Harvard Medical School (HMS) is one of the graduate schools of Harvard University. ...
This article is about the Dutch painter. ...
Painting by Rembrandt self-portrait Detail from Las Meninas by Diego Velazquez, in which the painter portrayed himself at work For the computer graphics program, see Corel Painter. ...
Medieval Art Main article: Medieval art Art during Medieval times was almost exclusively concerned with Christianity. ...
Because Rembrandt did not have normal binocular vision, even when he had both eyes open he used only one for many visual tasks. This could have helped him to flatten images as he saw them, and then put them onto the two-dimensional canvas. In the author's words: Dimension (from Latin measured out) is, in essence, the number of degrees of freedom available for movement in a space. ...
Canvas is an extremely heavy-duty fabric used for making sails, tents, marquees, backpacks, and other functions where sturdiness is required. ...
- Art teachers often instruct students to close one eye in order to flatten what they see. Therefore, stereoblindness might not be a handicap -- and might even be an asset -- for some artists.
See also Amblyopia, or lazy eye, is a disorder of the eye. ...
Binocular rivalry is a phenomenon of visual perception in which perception alternates between different images presented to each eye. ...
Diplopia, commonly known as double vision, is the perception of two images from a single object. ...
Eye dominance (sometimes called eyedness) refers to the tendency to use one eye more than the other in certain tasks involving precise hand-eye coordination and a reasonably distant target. ...
Eye movements are the voluntary or involuntary movements of the eye. ...
The field of view is the part of the observable world that is seen at any given moment. ...
Monocular vision is vision in which each eye is used separately. ...
Orthoptics, which literally means straightening of the eyes, dates back to the 1850s. ...
It has been suggested that Stereoscopic vision be merged into this article or section. ...
Stereo card image modified for crossed eye viewing View of Manhattan, c. ...
For the protein Strabismus, see Strabismus (protein) Strabismus, also known as heterotropia, squint, crossed eye, cockeyed, wandering eye, or wall eyed, is a condition in which the eyes are not properly aligned with each other. ...
This article or section does not cite its references or sources. ...
Vision therapy, also known as visual therapy or visual training, is a broadly-defined set of treatment programs related to the improvement of visual health and comfort. ...
External links |
Feeds |
Contact