retake the huge list of outstanding items . Next on the list is "stereopsis" but I was going to be a very weighty article, so first I will talk about what that implies that we have two eyes, and that will serve for the next article where and we'll get to heart of what is vision tridimiensional.Casi all humans are born with two eyes, like the vast majority of vertebrate animals. And yet, people just have to see an image concept is as if only we had a visual organ. If both eyes have healthy and we covered one with the other can read and see far and near. Our visual acuity would always be 100%. So, why do we need to have two eyes?. "For if one stops working?. Actually it is for more things, but schematically, the advantages of having two eyes are: - Increase our visual field-Get a virtual image "improved" using the two images coming from each eye. This is what I would call proper binocular vision, and binocularity.
Expanding the visual field
A human eye can perceive only what is exactly in front of you, what is left to one side can be seen within a certain range (although Peripheral vision is less clear, is enormously helpful.) In the horizontal plane, a human eye spans 120 degrees. When the eye is looking straight ahead, the visual field on the outside (ie, right in the right eye and counterclockwise in the left eye) is 90 º or 95 º. And on the inside (the nose) of about 60 degrees. Therefore, the "corner of my eye" we can cover much visual field, but on the inside hinders us nose and nasal bridge. Of course, moving the eye and head 150 degrees we move those around us, and that coordination between eye movements and neck do we have a perception of our environment rather complete.
But if we consider the two eyes working simultaneously, the whole visual field is extended to 180 degrees (or slightly more). Not bad. That means that when we do activities that require peripheral vision such as driving, notice quite a difference if we go with one eye covered. The road ahead we see eye uncovered equally clear, but cars come down the side of eye covered, do not see them until they cross in front of us. As driving is most noticeable when not using the left eye because overtaking and traffic the other direction we come from the left.
combining the information from both eyes
Each separate eye has a visual field of about 150 degrees, but the eyes do not work independently on the contrary, both eyes are focusing at the same point. If the human visual system was designed like a chameleon, acting so that each eye separately, could look at different areas and could have a whole field of view up to 300 º. But the opposite is true, both eyes focus at the same point. That means that much of the visual field of one eye overlaps with another. That is, an object that we see with one eye, if you're not peripheral, we also see another. Therefore, the brain receives information "redundant," a large part of the visual field is perceived by both eyes. This has two advantages: - Firstly, a possible defect or problem in one eye, is solved by another. As an easy example: the visual field of one eye has a so-called blind spot, which is a small area where we see (in this article by my colleague Shora is well explained). This will go unnoticed for several reasons and one of the reasons is that the blind spot of one eye is paid for by the other, which in this area that other eye sees well. Another example because where one eye "covers" the failure of another, when displayed in a vitreous opacities, the "little threads" or "points" black, which I explained in this article .- It allows us a better view of the three dimensions. We'll explain in the following article. Advantages
partially excluding
If we turn to this idea, the two advantages offered by having two eyes, are excluded to some extent. The increase in visual field when using both eyes is obtained precisely because of the field do not share the eyes, which does not overlap. That is, the area is not binocular. In particular if humans are around 30 degrees on each side externa.Y other hand, the advantages of seeing a part of our environment with both eyes at once we get it precisely because of the visual field area is common to both. Therefore, if some fields overlap visual visual field will be much together but little binocularity, and if there will be much overlap much binocularity but little increase in overall visual field. In our case we have a lot of binocular field, approximately 120 ° in different animals, depending on how the eyes are placed on the face and how they coordinate their actions, get more advantages of one type or another. Ever greater sacrifices peripheral field binocularity, and the same in reverse: many sacrifices binocularity periférico.Tomemos field such birds. They have a very sharp head, and his eyes are on each side: one clearly goes to the left and one right. Just a small angle from the front in which both eyes can see the same object. In this case, the birds are slaughtered for binocularity have a very wide visual field. In general, almost all have a common visual field of more than 270 degrees, and many are close to 360 º. So you can see almost any angle. By contrast, their perception of three dimensions is less than other especies.Por other hand, there are the primates. The monkeys initially used the trees (and many species of primates still do) to escape predators, food, travel, etc. It was essential that it could calculate the distance to climb or jump from branch to branch. So in your case is important to have good binocularity, to get a good view in three dimensions. Because the monkeys face is not sharp and the eyes are focused forward, much of the visual field is common for both eyes. Of course, that means they can not have a visual field as wide as a bird, ejemplo.Y we, as primates, have the same features as our binocularity is good. The binocularity
We're talking all the time on this concept, but we have only explained how binocular vision. What gives us that the visual fields of each eye overlap? In humans, binocularity is the normal situation, and requires several conditions have to give. If one fails, do not get binocular.Los vision requirements include: - The two eyes must be focused in one place. That means they have to look the same object. When this can not have a squint. This coordination between eye and another has to be strict, millimeter. Will not work with one eye look "more or less" you are facing the other. The central vision in one eye has to match exactly with the center of the other eye. So when we move the eye, both eyes move together and parallel. Strictly speaking the eyes are not parallel, but their axes are on a converging path in the object set: a line from the center of the retina, passes through the center of the cornea and reaches the object. In order to join each of the two axes. What happens is that when the object is far enough from these converging lines are almost parallel .- The brain has to be "learned" to see with both eyes. Of the two theoretical images coming from each eye, the brain gets "create" which is a mixture of both. Learning is needed at the beginning of our life .- We need to have an acceptable vision for both eyes. If one eye sees nothing, but all other requirements are met, it is logically impossible to have binocular vision. Reduced vision in one or both eyes may reduce binocularity (ie, we have, say "binocularity partial ") These are the requirements for binocular vision. But what exactly is the "binoculars"?. Then we provide 3 features, and each is based on the prior. That is, ordered in the following list, the 2 nd needs to be of 1, and 3 º needs the 2 nd. It may be the case then you have only the 1 st property, or have the 1 º and 2 º, or have all three (which we discussed in "binocularity partial) The features are: - Merger Motor: The ability to focus exactly at the same site with two eyes, it means that (almost) any time the eyes are perfectly aligned. This implies a complex mechanism in which if one eye starts to wander, without automatically focuses and we realize we do not see any movement. If the quality of the image from each eye is sufficient, and childhood was developed binocular vision in the brain, we have this resource of motor fusion. This resource a good way to avoid that we misaligned eyes. Although there is a tendency to squint, to some extent the merger will monitor and avoid driving strabismus. In fact, this is unusual: most of us have what is called "latent strabismus." Near vision or far, the visual axes will often have a slight tendency separated or crossed too. And never (or rarely) we will see, precisely because the motor fusion inhibits this trend and we can guarantee a correct alignment .- sensory fusion: the brain "fuses" the two images into one. Therefore, for a good part of what we see, perceive objects through two different sites. The basic form of sensory function simply involves the use of the two images, so that a small defect in the image of an eye can compensate with the other .- Stereopsis: Also called three-dimensional vision. It is the result of good sensory fusion. Examples
To understand the above, nothing better than a few case studies. We have a person who by circumstance, completely lost and quickly set the vision in one eye. The requirements for binocularity, we said that acceptable vision is needed for each eye. In this case, of course, lose binocular vision. And as we have completely lost vision in one eye, loss of binocularity is complete. Therefore, we have no motor fusion, or sensory fusion or stereopsis. We said that the motor fusion is a kind of "protection" against strabismus as the eye can not see, can go slowly creeping. And so it is often the case that over time displayed a squint, and the cause is what I explicado.Ya the way, one can understand one reason why the blind are usually wearing dark glasses. Blind eyes are not parallel, often have strabismus, and is aesthetically more acceptable goggles that cover the ojos.Pongamos another example, now think that we lose sight (of one or both eyes) but not as much as the previous case. Now assume that a person who needs to graduation, has not corrected with glasses or contact lenses. Binocularity requirements for compliance, at least in part. Therefore, the first "step" what have binocular vision, ie the motor fusion. That person will not have to squint not wearing glasses. But not complete sensory fusion and stereopsis may not be achieved. Therefore, if you see a movie at a cinema in 3D, is likely to fail to appreciate the feeling of seeing in three dimensiones.Otro example, a person with a squint of a lifetime. Strabismus can be large and noticeable, or it may be so small that it goes unnoticed. This case is similar to the first example, as soon as there is a small (or large) misalignment of the eyes almost completely lost binocularity. But unlike the first example, here is something that happens suddenly, but is the normal situation of the patient. So there will be changes in strabismus. But when the eyes are diverted, it is normal that there is no sensory fusion. That is, the brain uses both eyes to see. Choose one, and ignores the information from the other (this "loss" in a sense has its advantage, strabismus because these children do not suffer from double vision, something you do often occur in adult strabismus). In strabismus that are easily noticed, the eye that is "ignored" is that it is biased. In these cases, no stereopsis, so that neither the film in 3D or three-dimensional sheets (those of the "magic eye") will serve to mucho.De However, in cases of strabismus usually does not cause great surprise that perception D fails. Intuitively, the patient knows that the wandering eye "no use" like a normal person. Is most striking, however, a case of strabismus small, so small that nobody has realized that the person turns the eye forever. Or, even, may distort the child's eye was already resolved, but could not develop binocular vision. In either case, and other (a lazy eye intensive, for example), we find a normal person without strabismus (apparent) and with a vision (visual acuity) was also normal. You may find that you do not see the three dimensions in the 3D movie, or one of those blades 3D.Pero good that's a subject of this article.
Expanding the visual field A human eye can perceive only what is exactly in front of you, what is left to one side can be seen within a certain range (although Peripheral vision is less clear, is enormously helpful.) In the horizontal plane, a human eye spans 120 degrees. When the eye is looking straight ahead, the visual field on the outside (ie, right in the right eye and counterclockwise in the left eye) is 90 º or 95 º. And on the inside (the nose) of about 60 degrees. Therefore, the "corner of my eye" we can cover much visual field, but on the inside hinders us nose and nasal bridge. Of course, moving the eye and head 150 degrees we move those around us, and that coordination between eye movements and neck do we have a perception of our environment rather complete.
But if we consider the two eyes working simultaneously, the whole visual field is extended to 180 degrees (or slightly more). Not bad. That means that when we do activities that require peripheral vision such as driving, notice quite a difference if we go with one eye covered. The road ahead we see eye uncovered equally clear, but cars come down the side of eye covered, do not see them until they cross in front of us. As driving is most noticeable when not using the left eye because overtaking and traffic the other direction we come from the left. combining the information from both eyes Each separate eye has a visual field of about 150 degrees, but the eyes do not work independently on the contrary, both eyes are focusing at the same point. If the human visual system was designed like a chameleon, acting so that each eye separately, could look at different areas and could have a whole field of view up to 300 º. But the opposite is true, both eyes focus at the same point. That means that much of the visual field of one eye overlaps with another. That is, an object that we see with one eye, if you're not peripheral, we also see another. Therefore, the brain receives information "redundant," a large part of the visual field is perceived by both eyes. This has two advantages: - Firstly, a possible defect or problem in one eye, is solved by another. As an easy example: the visual field of one eye has a so-called blind spot, which is a small area where we see (in this article by my colleague Shora is well explained). This will go unnoticed for several reasons and one of the reasons is that the blind spot of one eye is paid for by the other, which in this area that other eye sees well. Another example because where one eye "covers" the failure of another, when displayed in a vitreous opacities, the "little threads" or "points" black, which I explained in this article .- It allows us a better view of the three dimensions. We'll explain in the following article. Advantages
partially excluding If we turn to this idea, the two advantages offered by having two eyes, are excluded to some extent. The increase in visual field when using both eyes is obtained precisely because of the field do not share the eyes, which does not overlap. That is, the area is not binocular. In particular if humans are around 30 degrees on each side externa.Y other hand, the advantages of seeing a part of our environment with both eyes at once we get it precisely because of the visual field area is common to both. Therefore, if some fields overlap visual visual field will be much together but little binocularity, and if there will be much overlap much binocularity but little increase in overall visual field. In our case we have a lot of binocular field, approximately 120 ° in different animals, depending on how the eyes are placed on the face and how they coordinate their actions, get more advantages of one type or another. Ever greater sacrifices peripheral field binocularity, and the same in reverse: many sacrifices binocularity periférico.Tomemos field such birds. They have a very sharp head, and his eyes are on each side: one clearly goes to the left and one right. Just a small angle from the front in which both eyes can see the same object. In this case, the birds are slaughtered for binocularity have a very wide visual field. In general, almost all have a common visual field of more than 270 degrees, and many are close to 360 º. So you can see almost any angle. By contrast, their perception of three dimensions is less than other especies.Por other hand, there are the primates. The monkeys initially used the trees (and many species of primates still do) to escape predators, food, travel, etc. It was essential that it could calculate the distance to climb or jump from branch to branch. So in your case is important to have good binocularity, to get a good view in three dimensions. Because the monkeys face is not sharp and the eyes are focused forward, much of the visual field is common for both eyes. Of course, that means they can not have a visual field as wide as a bird, ejemplo.Y we, as primates, have the same features as our binocularity is good. The binocularity
We're talking all the time on this concept, but we have only explained how binocular vision. What gives us that the visual fields of each eye overlap? In humans, binocularity is the normal situation, and requires several conditions have to give. If one fails, do not get binocular.Los vision requirements include: - The two eyes must be focused in one place. That means they have to look the same object. When this can not have a squint. This coordination between eye and another has to be strict, millimeter. Will not work with one eye look "more or less" you are facing the other. The central vision in one eye has to match exactly with the center of the other eye. So when we move the eye, both eyes move together and parallel. Strictly speaking the eyes are not parallel, but their axes are on a converging path in the object set: a line from the center of the retina, passes through the center of the cornea and reaches the object. In order to join each of the two axes. What happens is that when the object is far enough from these converging lines are almost parallel .- The brain has to be "learned" to see with both eyes. Of the two theoretical images coming from each eye, the brain gets "create" which is a mixture of both. Learning is needed at the beginning of our life .- We need to have an acceptable vision for both eyes. If one eye sees nothing, but all other requirements are met, it is logically impossible to have binocular vision. Reduced vision in one or both eyes may reduce binocularity (ie, we have, say "binocularity partial ") These are the requirements for binocular vision. But what exactly is the "binoculars"?. Then we provide 3 features, and each is based on the prior. That is, ordered in the following list, the 2 nd needs to be of 1, and 3 º needs the 2 nd. It may be the case then you have only the 1 st property, or have the 1 º and 2 º, or have all three (which we discussed in "binocularity partial) The features are: - Merger Motor: The ability to focus exactly at the same site with two eyes, it means that (almost) any time the eyes are perfectly aligned. This implies a complex mechanism in which if one eye starts to wander, without automatically focuses and we realize we do not see any movement. If the quality of the image from each eye is sufficient, and childhood was developed binocular vision in the brain, we have this resource of motor fusion. This resource a good way to avoid that we misaligned eyes. Although there is a tendency to squint, to some extent the merger will monitor and avoid driving strabismus. In fact, this is unusual: most of us have what is called "latent strabismus." Near vision or far, the visual axes will often have a slight tendency separated or crossed too. And never (or rarely) we will see, precisely because the motor fusion inhibits this trend and we can guarantee a correct alignment .- sensory fusion: the brain "fuses" the two images into one. Therefore, for a good part of what we see, perceive objects through two different sites. The basic form of sensory function simply involves the use of the two images, so that a small defect in the image of an eye can compensate with the other .- Stereopsis: Also called three-dimensional vision. It is the result of good sensory fusion. Examples
To understand the above, nothing better than a few case studies. We have a person who by circumstance, completely lost and quickly set the vision in one eye. The requirements for binocularity, we said that acceptable vision is needed for each eye. In this case, of course, lose binocular vision. And as we have completely lost vision in one eye, loss of binocularity is complete. Therefore, we have no motor fusion, or sensory fusion or stereopsis. We said that the motor fusion is a kind of "protection" against strabismus as the eye can not see, can go slowly creeping. And so it is often the case that over time displayed a squint, and the cause is what I explicado.Ya the way, one can understand one reason why the blind are usually wearing dark glasses. Blind eyes are not parallel, often have strabismus, and is aesthetically more acceptable goggles that cover the ojos.Pongamos another example, now think that we lose sight (of one or both eyes) but not as much as the previous case. Now assume that a person who needs to graduation, has not corrected with glasses or contact lenses. Binocularity requirements for compliance, at least in part. Therefore, the first "step" what have binocular vision, ie the motor fusion. That person will not have to squint not wearing glasses. But not complete sensory fusion and stereopsis may not be achieved. Therefore, if you see a movie at a cinema in 3D, is likely to fail to appreciate the feeling of seeing in three dimensiones.Otro example, a person with a squint of a lifetime. Strabismus can be large and noticeable, or it may be so small that it goes unnoticed. This case is similar to the first example, as soon as there is a small (or large) misalignment of the eyes almost completely lost binocularity. But unlike the first example, here is something that happens suddenly, but is the normal situation of the patient. So there will be changes in strabismus. But when the eyes are diverted, it is normal that there is no sensory fusion. That is, the brain uses both eyes to see. Choose one, and ignores the information from the other (this "loss" in a sense has its advantage, strabismus because these children do not suffer from double vision, something you do often occur in adult strabismus). In strabismus that are easily noticed, the eye that is "ignored" is that it is biased. In these cases, no stereopsis, so that neither the film in 3D or three-dimensional sheets (those of the "magic eye") will serve to mucho.De However, in cases of strabismus usually does not cause great surprise that perception D fails. Intuitively, the patient knows that the wandering eye "no use" like a normal person. Is most striking, however, a case of strabismus small, so small that nobody has realized that the person turns the eye forever. Or, even, may distort the child's eye was already resolved, but could not develop binocular vision. In either case, and other (a lazy eye intensive, for example), we find a normal person without strabismus (apparent) and with a vision (visual acuity) was also normal. You may find that you do not see the three dimensions in the 3D movie, or one of those blades 3D.Pero good that's a subject of this article.
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