Eye diseases. The concept of progressive myopia (the most important)

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Eye diseases. The concept of progressive myopia (the most important)

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42. The concept of progressive myopia

Progressive myopia is any type of nearsightedness that is a deterioration in distance vision. There is information about the antecedent of false myopia true, i.e., this is a condition in which there is a more or less rapid and pronounced drop in visual acuity at a distance due to spasm, or tension, of accommodation. Nevertheless, after the spasm is eliminated with the help of cycloplegic agents (atropine, scopolamine, homatropine), vision is restored to normal, and refractometry reveals emmetropia or even farsightedness.

In recent decades, myopia (myopia) more often began to develop in preschoolers who, during their upbringing, had a high visual load in combination with a sedentary lifestyle, poor nutrition and weakening of the body due to frequent illnesses (tonsillitis, dental caries, rheumatism, etc.). Among students in first and second grades, myopia occurs in 36%, in third and fourth grades in 6%, in seventh and eighth grades in 16%, in ninth and tenth grades in more than 20%. Severe (high, advanced) myopia causes over 30% of low vision and blindness from all eye diseases; it is an obstacle to the choice of many professions.

The mechanism of development of myopia that occurs during childhood consists of three main links, such as:

1) visual work at close range (weak accommodation);

2) burdened heredity;

3) weakening of the sclera, violation of trophism (intraocular pressure).

Consequently, according to the predominance of certain causes of development, myopia can be conditionally divided into accommodative, hereditary and scleral.

The development of each of these forms of myopia over time leads to irreversible morphological changes in the eyes and a pronounced decrease in visual acuity, which often does not improve much or does not improve at all under the influence of optical correction.

The main reason for this is a significant lengthening of the eye axis: instead of 22-23 mm, it reaches 30-32 mm or more, which is determined using an echo-ophthalmograph. If myopia progresses over the course of a year by less than 1,0 diopters, then it is conditionally considered benign, and if the increase is 1,0 diopters. and more malignant. However, it is not only a matter of progression, but also of the size and changes in the intraocular structures (vitreous body, choroid, retina, optic nerve).

A large stretching of the eyes during myopia leads to an expansion of the palpebral fissure, as a result of which a kind of bulging is created. The sclera becomes thinner, especially in the area of attachment of the lateral muscles and near the edge of the cornea. This can be determined with the naked eye by the bluish tint of the cornea due to translucence of the choroid, and sometimes by the presence of anterior staphylomas of the sclera. The cornea also stretches and thins. The anterior chamber of the eye deepens. Mild iridodonesis (trembling of the iris), destruction or liquefaction of the vitreous body may occur. Depending on the genesis and magnitude of myopia, changes in the fundus occur.

Author: Shilnikov L.V.

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