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Short-sightedness, far-sightedness, astigmatism
Short-sightedness, far-sightedness, astigmatism – three illnesses of organs of sight which have the identical nature. In order that it is better to understand them, at first it is necessary to remember how an eye of the person is arranged. Let's remind that an eye works as the collecting lens, that is beams getting into it pass through a cornea and a crystalline lens owing to what refract and gather on a retina.
The image focused on a retina is perceived by us as what was seen. Respectively if the point of focus is for one reason or another displaced, it leads to changes in sight. In one case of people well sees distant objects, in other case on the contrary, near. But also short-sightedness, both far-sightedness, and an astigmatism are disturbances of a normal refraction, that is ability of an eye to light refraction.
So, what changes in the refracting environments can happen and what they lead to.
If the crystalline lens or a cornea refract light too strongly, then beams will agree not on a retina, and before it. In this case short-sightedness or as it is called still, a myopia takes place. The same occurs if the eyeglobe takes the extended form, that is the retina "moves away" from a focus point.
As a result of people rather well sees what is close as from a subject a large number of beams is reflected and the image turns out rather accurate. But afar sight significantly decreases. The myopia meets much more more often than far-sightedness and an astigmatism and is characteristic occupational disease at the people who are constantly working at the computer (a so-called computer syndrome).
There are several classifications of this illness of eyes. We already mentioned one of them: refraction (when strengthening a refractivity of a crystalline lens or cornea) and axial (at change of an optical axis). Besides short-sightedness, as well as other diseases, divide on inborn and acquired. At supervision over the patient in dynamics the myopia shares on progressing and not progressing.
Far-sightedness has the return properties. Instead of being focused on a retina, rays of light gather in an imaginary point behind a retina, that is on a retina the vague image appears. Far-sightedness or as it is called still, the hypermetropia, has the same classification, as short-sightedness. However unlike it the person can see well remote objects, perceiving everything on proximity in a "indistinct" look.
And, at last, the astigmatism is a situation at which various sites of an eye have a different refractivity. That is light beams cannot be focused in one point as all of them refract with different coefficient. The astigmatism can have partly the same properties as short-sightedness or far-sightedness depending on in what party the index of refraction changes.
For completeness of illumination of the matter, we will note still such illness as age far-sightedness. The matter is that with age eyes of the person lose the ability to accommodation, that is fast setup of clearness of perception of the image of objects in various conditions. As a result of at a short distance eyes it cannot be focused. Of course, age far-sightedness though has similar signs with far-sightedness usual, differs from the illness of the same name in several other nature. But not to mention it in this article would be a mistake.
Symptoms of short-sightedness, far-sightedness and astigmatism
In principle, the main signs of emergence of the described diseases of eyes, we already mentioned. So, the main symptoms of short-sightedness this deterioration in sight at a great distance, the main symptoms of far-sightedness – vague perception of close objects, and symptoms of an astigmatism are characterized by "floating" changeable sight.
Most often we notice deterioration in sight accidentally when we cannot read the book without points or on the contrary, hardly we distinguish number of the approaching transport. At this stage it is possible to say that you have an eye illness which demands treatment. At the same time it is considered that some aberrations are quite admissible. For example, the astigmatism at which distinctions of a refractivity in different points make to one dioptry is considered normal.
To you quite in power to define sight independently, using special tests with tables. Therefore we will stop on sight diagnosis separately.
Diagnosis of refraction problems of an eye
The easiest and most widespread way of determination of sight – the table. As you know, in such tables ranks of letters of the different size and a ring with cuts on which check sight of the people who are not knowing the alphabet are provided. This test at the correct carrying out allows to define short-sightedness or far-sightedness on each of eyes separately.
All other diagnostic methods it is slightly more difficult. Instead of changing the size of letters (that is images), in certain cases select the correct attachment lens which "returns" focus on a retina. Oculists in salons of optics resort to this method, choosing suitable glasses.
The remained types of inspections "study" eye elements, that is define curvature of a cornea, inspection of a pupil by exact rulers in an expanded state and others.
Treatment of short-sightedness, far-sightedness and astigmatism
First of all, it is necessary to understand that any of these three diseases of eyes is disturbances in a form or structure of components of an eye. Therefore drug treatment can render only short-term effect of improvement of sight and has exclusively preventive character.
So, by means of atropine or a phenylephine hydrochloride it is possible to expand a pupil that, of course, will increase sight clearness. Also use of piracetam or a tsinozorin expands vessels and improves blood circulation in a brain. But the positive effect passes with administration of drugs. Reception of vitamins allows to remove insignificant symptoms of short-sightedness, far-sightedness and astigmatism, but it is not necessary to speak about full treatment.
Really operating methods which can return a normal refraction mean correction of disturbances. And it is natural that it is about correction, but not about treatment of short-sightedness, far-sightedness or astigmatism.
Allocate three ways of correction:-point, contact and surgical. Points are appointed or at initial stages or when more difficult methods are inapplicable for one reason or another. Surgical correction is shown at a sharp exacerbation of diseases and its continuous progressing.
Prevention of short-sightedness, far-sightedness and astigmatism
Short-sightedness, far-sightedness and astigmatism in many cases it would be possible to avoid if the patient conformed to certain simple rules. Their essence is reduced to leveling of the actions menacing to changes in optical tools of an eye, and performance of exercises which strengthen these tools.
Exercises these quite simple and widely known: fast switching of focusing from close objects on distant, frequent blinking, rotation of eyes, switching from the monitor or the TV each 20 minutes on the quiet, not blinking objects.
If to add control over the actions to regular exercises, that is to read always at the correct lighting and without lying, not to watch continuously for hours TV, not to abuse addictions, to protect eyes from damages, then problems with a refraction can be avoided. Believe, it is worth it, except deterioration in sight the cataract can become an effect of short-sightedness, and this disease is even more dangerous.
Section: Diseases of eyes