Myopia (myopia) in children

Nearsightedness (myopia) is a type of disproportionate refraction in which parallel rays of light, refracted by the optical system of the eye, are focused in front of the retina.

A distinction is made between congenital and acquired myopia. In congenital myopia, the discrepancy between the optical (refractive power of the cornea and lens) and anatomical (length of the anterior-posterior axis of the eye) components of refraction occurs during intrauterine development. In this case, too strong refraction of the eye can be caused by a combination of high refractive power of its optical apparatus with a normal length of the axis. In this case, according to the classification of E.Zh. Tron (1947), refractive myopia occurs. A combination of weak or normal refractive power of optical surfaces with a longer axis (axial myopia) is possible. However, no matter what the congenital myopia is (axial, refractive or mixed), its progression always occurs due to an increase in the length of the eye.

Congenital myopia is detected in 1.4-4.5% of children aged 1 year. In newborns, the frequency of myopic refraction is much higher, reaching 15% and even 25-50% (in premature babies), but in most cases this is a transient weak myopia, which disappears during the first months of life as a result of the action of so-called emmetropizing factors: weakening of the refractive power of the cornea and lens and deepening of the anterior chamber.

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Prevalence of myopia (nearsightedness) in children

Although the prevalence of myopia (nearsightedness) depends mainly on hereditary factors and environmental conditions, the age of the patient also plays a certain role in its frequency of occurrence. Thus, at the age of up to 1 year, myopic refraction occurs in 4-6% of children, while in preschool age the incidence of myopia does not exceed 2-3%. As the child grows older, the incidence of myopia increases. At the age of 11-13 years, myopia is observed in 4% of children, and when examining people over 20 years of age, myopia occurs in 25% of cases. It is well known that premature babies are especially prone to the development of myopia; there are reports that the incidence of myopia in this group ranges from 30 to 50%.

Myopia (nearsightedness) is a common cause of visual disability in all population groups. Vision loss occurs both due to refractive disorders and as a result of concomitant pathological changes in the visual organ and general disorders.

Classification of myopia

Clinical classification of myopia by Professor E.S. Avetisov

• By degree:
  • weak - up to 3.0 Dpt;
  • average - 3.25-6.0 Dptr;
  • high - 6.25 D and above.
• According to equality or inequality of refraction of both eyes:
  • isometropic;
  • anisometropic.
• By the presence of astigmatism.
• By age of occurrence:
  • congenital:
  • early acquired:
  • arising in school age;
  • late acquired.

Classification of myopia

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Causes of myopia in children

In the etiology of congenital myopia, the leading role is given to heredity (55-65%) and perinatal pathology.

Congenital myopia is usually characterized by a high degree, an increase in the length of the anteroposterior axis, anisometropia, astigmatism, a decrease in maximum corrected visual acuity, changes in the fundus associated with developmental anomalies of the optic nerve and macular region.

Acquired myopia appears in preschool (early acquired), school age, less often in adults, and its occurrence and progression is based on the elongation of the anterior-posterior axis of the eye.

In most cases, the visual acuity of the nearsighted eye, under optical correction with diverging lenses of the appropriate diopter, increases to normal values (1.0 or 6/6 or 20/20, depending on the measurement system). Such myopia is called uncomplicated. With complicated myopia, visual acuity not only at a distance but also at a close distance remains reduced even with full optical correction of refractive error. Such uncorrectable vision loss can be caused by amblyopia (cortical inhibition), dystrophic changes in the central part (macular zone) of the retina, its detachment, and clouding of the lens (cataract). In children, the most common cause of uncorrectable vision loss with myopia is amblyopia. It accompanies only congenital myopia of a high and, less often, moderate degree. The reason for its development is the prolonged projection of unclear images onto the retina (refractive amblyopia). An even more persistent decrease in vision is observed with anisometropic or unilateral congenital myopia (anisometropic amblyopia).

What causes myopia?

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Symptoms of complicated myopia

Both congenital and acquired myopia in the case of a progressive course can reach high degrees and be accompanied by the development of complications in the fundus - both in the posterior pole and in the periphery. High myopia with pronounced axial elongation and complications in the central zone of the retina has recently been called pathological. It is this myopia that leads to irreversible vision loss and disability. The second most common cause of vision loss in myopia is retinal detachment, which occurs against the background of dystrophic changes and ruptures in its peripheral parts.

Destructive changes also occur in the vitreous body, increasing as myopia progresses and playing an important role in the development of its complications. When the vitreous body is destroyed, complaints of floating opacities ("commas", "spiders") arise; with high myopia, posterior detachment of the vitreous body is possible, in which the patient notices a dark ring floating in front of the eye in a circle.

Symptoms of Nearsightedness (Myopia)

Correction of myopia

In congenital myopia, early and correct correction is of particular importance as the main means of preventing and treating amblyopia. The earlier glasses are prescribed, the higher the corrected visual acuity and the lower the degree of amblyopia. Congenital myopia should be detected and corrected in the first year of a child's life. In young children with anisometropia up to 6.0 D, correction with glasses is preferable. Children easily tolerate a difference in the strength of lenses in paired eyes up to 5.0-6.0 D. Glasses are prescribed with a strength of 1.0-2.0 D less than the objective refractometry data under cycloplegia. Correction of astigmatism over 1.0 D is mandatory. It should be taken into account that with congenital myopia, refraction may weaken in the first years of life, so monitoring and appropriate correction changes are necessary.

Correction (treatment) of myopia

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