Strabismus and amblyopia: the cause of their occurrence
Since we have two eyes, it is obvious that in the process of sight two images should be formed. In order for both these images to merge in the brain into one, it is necessary that the interaction of the two organs of vision is perfectly harmonious. When looking at a remote object, the two visual axes must be parallel, and when looking at an object from a distance that is less than infinity( in practice, this means a distance of less than 20 feet), they must intersect at the same degree.
The absence of such harmony of action is known as strabismus, or strabismus. Strabismus is one of the eye defects that cause the greatest suffering not only because of decreased vision, but also because of the lack of symmetry in the most expressive part of the face, which leaves an unpleasant impression on the appearance of a person. This condition is one of those that for a long time confuses the ophthalmological science. Despite the fact that theories of its origin, described in the textbooks, seem acceptable for a number of cases, other cases they leave without any explanation. In addition, it is recognized that all methods of treating strabismus are very vague in their results.
The idea that the lack of harmony in eye movement is associated with a corresponding lack of harmony in the strength of the muscles turning them in the eye sockets seems so natural that at one time this theory was universally recognized. Operations based on it, at that time were very fashionable, but now most specialists recommend them only as a last resort. True, many people have helped, but even in the best case, the correction of strabismus in this way is very approximate, and in many cases the condition even worsens. At the same time, it is hardly possible to hope for the restoration of binocular vision - the ability to merge two visual images into one.
Muscle theory in fact so poorly picked up the evidence that when it was suggested that strabismus is a condition caused by refractive anomalies( hypermetropia was considered responsible for the production of convergent strabismus and myopia for the production of divergent strabismus), this theory was adopted everywhere. But she too was unsatisfactory, and now the opinions of physicians have split between different theories. One theory attributes this condition in most cases to a defect of not muscles, but innervation, and it has won many supporters. Another theory draws particular attention to the lack of capacity for so-called fusion and recommends using prisms or other measures for its development. The third theory states that this anomaly of the eyes is the result of an irregular shape of the ocular cavity and, since it is impossible to change this state, protects the operations as a means of neutralizing its influence.
To make each of these theories consistent, it is necessary to get rid of superficial explanations from many unpleasant facts. The indeterminate result of operations on the eye muscles is sufficient to cast a shadow of suspicion on this theory linking strabismus to any abnormality of muscles. In this case, there were many cases of significant paralysis of one or several muscles without the appearance of any strabismus. Moreover, weakening of paralysis could not ease the strabismus, as well as a decrease in strabismus did not relieve paralysis. One well-known ophthalmologist met with so many case histories where training designed to develop fusion ability did not do any good, that in such cases he began to recommend surgery on the muscles. Another ophthalmologist, drawing attention to the fact that most hypermetropics does not mow, was forced to admit that hypermetropia does not cause any help from the circumstances of strabismus.
The fact that the state of vision does not play a significant role in the appearance of strabismus is confirmed by a multitude of facts. Indeed, strabismus is usually accompanied by refractive error anomalies, but in some people strabismus exists only with a very slight refraction anomaly. It is also true that many people with converging strabismus have hypermetropia. Nevertheless, many other people with strabismus do not have hypermetropia. Some people with converging strabismus have myopia. A person can also have a convergent strabismus with one normal eye, and another - hypermetropic, myopic or blind.
Usually the sight of the eye turned inward is lower than the eyesight that looks straight. Nevertheless, there are cases when the eye with poor eyesight looks directly, and the eye with a better vision is turned inwards. If both eyes of a person are blind, then it can be that both of them will look straight or one straight and the other inside. At one good, and other blind eyes both can look directly. As a rule, the more blind the eye, the more noticeably the strabismus. However, there are often exceptions, and in rare cases, eyes with almost normal eyesight can stubbornly look inside.
In addition, the strabismus can disappear and reappear. It may also be that the converging strabismus will turn into a divergent and again back into converging. With the same refraction anomaly, one person will have a strabismus, while the other does not. The third will mow not with the eye that the other. The fourth will first have to mow one eye, and then another. In the fifth case, the degree of strabismus will vary. One will be good without glasses or other types of treatment, and the other - with their application. The cure can be permanent or temporary, and relapses can happen with or without glasses.
No matter how the refraction anomaly was ignored, the sight of the mowing eyes is still worse than the eyesight, looking straight. In this case, the device usually does not show any obvious or sufficient reasons for this. The opinions of researchers differ as to whether such a curious visual impairment is the result of strabismus or whether the strabismus itself is its result. However, the prevailing view is that it is at least aggravated by the presence of strabismus, which is reflected in the name given to this condition amblyopia ex anopsia, which literally means "weakening vision due to nonuse".It is customary to associate ambiguity with the need to suppress the image given by the deflecting eye in order to avoid irritation from the double image. However, there are many eyes that mow, but without any manifestations of amblyopia. In turn, amblyopia was found in the eyes, which were never mowed.
The literature on this issue is full of hopelessness regarding the possibility of curing amblyopia. In popular publications of people who are concerned about the health of children, they convince that if a child has strabismus, treatment should be started immediately, so as not to lose sight of the mowing eye. According to the opinion of a well-known ophthalmologist, after achieving a child of six years, usually little can be done to improve the vision of the amblyopic eye. At the same time, another ophthalmologist claims that "the function of the retina never returns to normal again, even if the cause of the visual impairment is eliminated."It is also well known that if at some stage of life the vision of a good eye is lost, then the vision of the amblyopic eye often becomes normal. Moreover, the eye at one time can be amblyopic, and the other - stop it. If you cover something with a good eye, then the mowing eye can become so amblypy that it is unlikely to distinguish between daylight and darkness. But if both eyes are open, then the vision of the mowing eye can be found as good, if not better, as the sight of the eye-starter. In many cases, there was a transition of amblyopia from one eye to another.
Doubling of vision with strabismus is very rare. If it does take place, it often takes strange forms. When the eyes are turned inward, the image seen by the right eye should, according to all the laws of optics, be on the right, and the image seen by the left eye on the left. When the eyes are turned outward, the opposite picture is observed. But often the position of the images is reversed: the image of the right eye with a converging strabismus will be visible from the left, and the image of the left eye is to the right, while with the divergent strabismus we encounter the opposite case. This condition is known as "paradoxical diplopia", moreover, people with almost normal vision and with both eyes, clearly looking straight, can have both kinds of double vision.
All the proposed theories failed in an attempt to explain the facts described above, but it is known that in all cases of strabismus there may be a presence of tension, and also that following the disappearance of strabismus, as well as after the disappearance of amblyopia and refraction anomaly,decrease in tension. It is also known that all people with normal eyes can create a state of strabismus, making an effort to see. This is not such a difficult thing, and many children entertain themselves with such an occupation, which delivers to adults unnecessary anxiety due to fear of the possible transformation of temporary strabismus into a permanent one.
Converting strabismus is relatively easy. Children usually do this, trying to see the tip of their nose. The production of divergent strabismus is more difficult, but after training, people with normal eyes will be able to turn any eye, or both, at will. They can also learn to turn one eye up, and the other down, or one up, and the other outward at the desired angle. Indeed, with the help of the appropriate type of stress, it is possible to produce, if desired, virtually any form of strabismus. When an arbitrary( voluntary) strabismus is performed, a visual impairment is usually observed, and conventional methods of measuring muscle strength are likely to register muscle shortcomings corresponding to the nature of strabismus.