Myopia, or nearsightedness - a violation of view, in which a person can clearly see objects that are close to him, and objects farther away are blurred. Myopia develops when the eyeball is too long or if the cornea is too curved. As a result, the light entering the eye is focused correctly and distant objects appear hazy.
Myopia is a very common disorder; in some countries it is common in 30% of the population. Some studies support the theory that nearsightedness is hereditary. There is growing evidence that the factors accompanying the development of myopia, eye strain can be, for example, as a result of prolonged and regular computer work.
As a rule, myopia was first detected in children of school age. In most cases, this disturbance progresses up to about 20 years. However, the myopia can also develop in adults as a result of the DC voltage eyes, or certain diseases such as diabetes.
Myopia can also be linked to environmental factors and characteristics of professional activity. For example, some people blur distant objects observed only at night. This may be due to poor illumination or to increase the size of the pupil in the dark.
People who are engaged in work requiring a large voltage of view, can suffer from the symptoms of so-called false myopia. Remote objects may appear blurred due to them, because they are overtaxed eye mechanisms responsible for focusing. After prolonged use of the eyes can not change the focus and see clearly what is more or less far away. These symptoms tend to be of a temporary nature; vision can be restored after holidays. However, over time, a frequent eye strain can cause permanent visual impairment.
For the diagnosis of myopia can be used a variety of methods and tools as usual table for an eye examination and a more modern tools - phoropter and retinoscope. During the test using phoropter doctor puts before the eyes of the patient's various lenses and using retinoscope determines how the eye focuses light. For the diagnosis of myopia may also apply automatic instruments.
The main methods of treatment, or rather, are myopic glasses, contact lenses and eye surgery, the most common of which - laser vision correction
Laser vision correction - what is the most effective way?
. first selecting means, as a rule, are glasses - they are the easiest to use and safe. On the other hand, contact lenses provide a wider field of view. Operations in most cases effectively improve eyesight, but this method may not be suitable, not least - because of its relatively high cost.
In addition, there is a special therapy for people with nearsightedness cause spasm of the muscles responsible for focusing the eye. Such patients are recommended a variety of exercises that gradually improve vision.
How does the body of
The body of view - it is not only the eyes but also a part of the nervous system - the image of the eye is transmitted by the optic nerve to the brain.
Eye - a balloon (or eyeball), located in the eye slit. Inside the eye are transparent light-refracting medium - the lens, the vitreous and aqueous humor. The wall of the eye consists of three layers of the outer connective tissue, vascular and internal medium - retina.
The outer shell will protect your eyes from injury, it is transparent front (the cornea) and is part of the optical system. Choroid front called the iris. In the middle of the iris is a hole (the pupil), is under the iris ciliary body with the ciliary muscle, which changes the cutting or relaxing the convexity of the lens. The retina is made up of nerve receptors that are in the back of her perceived image. In the middle of the back of the eye is a place, which is in contact with the rays, the image becomes especially clear (the macula), next to it is the optic disc and blood vessels that nourish the eyeball.
System light-refracting eye refracts rays, which penetrate into the eye, the focus of this index (the place where the refracted rays crossed) gets to the retina and the optic nerve to the brain information is. The lens has the ability to flatten or round, changing its refractive power - this is called of accommodation (ciliary muscle contraction is provided).
The refractive power of the eye is called refraction, it is measured in diopters, comparing with the work of the lens. A diopter is a refractive power of a lens with a focal length of 1 m.
Myopia mild to moderate
Mild myopia - a violation of refraction to 3, 0 diopters, medium - 3, 0 to 6 diopters. Myopia mild to moderate rather than a disease, but an anomaly or peculiarity of view. Most often it is reflected in the fact that man is badly sees distant objects and squinting to better see them. Due to the constant narrowed his eyes at the short-sighted people who do not wear glasses or contact lenses, appear premature wrinkles. For myopia and is characterized by the appearance of "flies" in front of my eyes - small, moving together with a look of points.
In most cases, myopia is weak and requires only moderate correction glasses or contact lenses
Contact lenses - whether they can completely replace the glasses?
. Recently, for the treatment of myopia laser correction is applied: the laser removes a thin layer of the cornea, reducing its refraction.
High myopia is placed in violation of refraction up to 6, 0 diopters or higher. Since the anteroposterior dimensions of the eye during progressive myopia increasing rapidly, then increases and violation of refraction (elongation axis of the eye for 1 mm - a strengthening of myopia 3, 0 diopters). The appearance of such people is typical: convex eyes, eye slit open, the pupil expanded.
The high degree of myopia often can not be corrected with glasses. Slightly better are contact lenses, but they often do not help in such cases, patients prescribed telescopic glasses, which have the appearance of small binoculars. Surgical correction of vision in high myopia is to remove the lens and the installation is not his place specially chosen lens.
Progressive (malignant) myopia
Progressive myopia or malignant form is accompanied by a rapid increase of the eyeball, resulting in a stretchable meninges, and the development of complications caused by malnutrition retina. All these changes cause defects in the retina and can lead to detachment of it - a severe complication with severe visual impairment.
Malignant myopia in addition to vision correction requires a long konservativnogolecheniya.
Based on what the diagnosis of myopia
A diagnosis of myopia is made by typical complaints of the patient and confirmed by objective research:
- visual acuity with special lenses, correcting nearsightedness;
- skiascopy - observation of the movement of the light spot in the illuminated pupil during rotation ophthalmoscopic mirror; with normal vision, farsightedness
Hyperopia - than it is fraught?
Myopia - when visual acuity falls
less than 1 diopter light spot moves in one direction, while myopia above 1, 0 diopters - in the other;
- refractometry eye - measurement of refraction with the help of special equipment - refractometer;
- ophthalmoscopy - research the state of the fundus (the visible inner surface of the eyeball); inspection is carried out using an ophthalmoscope, identify complications of myopia;
- ultrasonic diagnostic techniques (can measure the length of the eyeball, and the thickness of the cornea at different sites).