the rays in the eye with myopiaNearsightedness (myopia) is one of the types of clinical refraction of the eye (see)in which parallel beams coming from objects after they refraction in the eye incorporate in focus ahead of the retina (Fig).
On the retina with myopia connect to focus only diverging rays from objects from the eye at close range (Fig., 2). In this regard, distant objects are perceived vaguely. The distance within which it is possible sharp vision depends on the degree of myopia higher myopia, the closer should be subject.
The development of myopia contribute unhygienic conditions visual work (bad lighting, work at a close distance and other). Hereditary predisposition to myopia can be set in the presence of adverse conditions. Myopia is usually begins in the school years, with age the level of it can grow.
There are three degrees of myopia: low - up to 3 diopters, average - from 3 to 6 diopters and high - more than 6 dioptres. Singled out as particular disease is severe or progressive nearsightedness, in which there are changes in the retina and in the fundus. Complications of this kind of myopia may be the retinal detachment (see), bleeding in the eye shell and others, leading to a significant decrease in vision and even blindness.
Diagnosis myopia is usually a doctor-ophthalmologist on the basis of definition of visual acuity (see) and other studies. All of seeking medical assistance complaints about poor vision or poor vision, should be directed to the doctor - ophthalmologist.
Treatment. To improve vision with myopia, the required correction with glasses (see) with the scattering glass. In complicated and progressive myopia require medication that is a doctor-ophthalmologist.
Retinal detachment requires surgical treatment.
Prevention of myopia is a removal of adverse conditions in visual work. You must follow the correct posture of children during the lessons, the observance of hygienic norms lighting in school and at home (see the Vision, Lighting). The great value has a General strengthening of an organism. When high myopia patients should avoid heavy physical activity.
You need to know that children often are born farsighted, and as they grow and increase the size of the eyeballs. To 9-10 years of life eyes be proportionate. However, in some children the growth of the eyeballs can continue. This leads to longer axis of the eye and tensile strength not only of sclera and internal membranes of eyes. Myopia develops in which all considered objects appear blurred, as if in a fog. This is because the light rays reflected from the deleted items due to high optical power refracting medium or large size of the eyeball, focus in front of the retina. On the contrary, from objects that are located nearby, rays of light are going on the retina and give it a clear image without significant stress the ciliary muscle. So myopic can spend hours to do the job for a minimum from the eyes of distance, including very small objects, not feeling visual fatigue.
The first sign of the disease is the reduction. However, very often myopia is not noticeable, as it develops first in one eye, and this defect of view for a long time remains unnoticed. Besides initially appears false myopia associated with excessive tension of the ciliary muscle. Gradually false myopia becomes true, it is stretching the eye anteroposterior direction. In this period, especially distinctly reveals a loss of efficiency of the ciliary muscle. There are three degrees of myopia: weak (up to 3 diopters), medium (3,25-6 diopters) and high (more than 6 dioptres).
In most cases, myopia is mild and moderate degree, and to 17-20 years the growth of its often suspended. This so-called stationary course of the disease, not entail adverse consequences. Only in order to see clearly into the distance, so people need to use glasses with light-scattering glass.
There are two main mechanisms of development of myopia: mismatch accommodation capacity eyes visual load and heredity. This defect is more common among physically impaired children with chronic tonsillitis, rheumatism, a tuberculosis, ricketsundergoing infectious or other severe diseases, excessive visual job at a short distance. Unfavorable sanitary and hygienic conditions and, first of all, poor lighting, and a sedentary lifestyle are often contribute to the emergence and development of myopia.
In recent years found that short-sighted more likely than healthy, meets posture, scoliosis and flat feet, which in turn negatively affects the state of internal organs, causing General fatigue.
In preschool and especially school age it is almost impossible to distinguish between stationary myopia from other forms of progressive, which, if no action is taken, often leads to blindness due to irreversible changes of vascular and latticed shells. The disease occurs mainly in children of school age. Not without reason in the recent past, even in the literature there was such a widespread concept of the school myopia.