Nearsightedness (myopia) in children
Last reviewed: 23.04.2024
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Nearsightedness (myopia) is a kind of disproportionate refraction, in which parallel rays of light, refracted by the optical system of the eye, gather in focus in front of the retina.
Distinguish between congenital and acquired myopia. With a congenital discrepancy between the optical (the refractive power of the cornea and the lens) and the anatomical (length of the anteroposterior axis of the eye), the components of refraction occur during the period of intrauterine development. At the same time, too strong refraction of the eye can be caused by a combination of the high refractive power of its optical apparatus with a normal axis length. In this case, according to E.Zh. Thron (1947), there is a refractive myopia. A combination of a weak or normal refractive force of optical surfaces with a longer axis (axial myopia) is possible. However, whatever the congenital myopia (axial, refractive or mixed), its progression always occurs due to an increase in the length of the eye.
Congenital myopia is diagnosed in 1.4-4.5% of children aged 1 year. In newborns, the frequency of myopic refraction is much higher, reaching 15% or even 25-50% (in premature infants), but in most cases it is a transient weak myopia that disappears during the first months of life as a result of the so-called emmetropic factors: weakening of the refractive power of the cornea and the lens and indentations of the anterior chamber.
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Prevalence of myopia (myopia) in children
Although the prevalence of myopia (nearsightedness) depends mainly on hereditary factors and environmental conditions, a certain role in the frequency of its appearance is played by the age of the patient. So, at the age of up to 1 year, myopic refraction occurs in 4-6% of children, while at preschool age the incidence of myopia does not exceed 2-3%. As the child grows up, the frequency of myopia increases. At the age of 11-13 years, myopia is observed in 4% of children, and in the examination of persons older than 20 years of age, myopia occurs in 25% of cases. It is well known that prematurity is particularly prone to the development of myopia; there are reports that the frequency of its occurrence in this group ranges from 30 to 50%.
Myopia (nearsightedness) is a common cause of vision impairment in all population groups. Reduction of vision occurs both in connection with refractive disorders, and as a result of concomitant pathological changes in the organ of vision and general disorders.
Classification of myopia
Clinical classification of myopia prof. Avetisova
- By degree:
- weak - up to 3.0 Dpt;
- average - 3,25-6,0 diopters;
- high - 6.25 D and above.
- By equality or inequality of refraction of both eyes:
- isometropic;
- anisometropic.
- By the presence of astigmatism.
- By age of occurrence:
- congenital:
- Early-acquired:
- emerged at school age;
- late acquired.
Causes of myopia (myopia) in children
In the etiology of congenital myopia, a leading role is assigned to heredity (55-65%) and perinatal pathology.
Congenital myopia usually has a high degree, an increase in the length of the anteroposterior axis, anisometropia, astigmatism, a decrease in the maximum corrected visual acuity, changes in the fundus associated with anomalies in the development of the optic nerve and the macular area.
The acquired myopia appears in preschool (early-acquired). School age, less often - in adults, and the basis of its appearance and progression is lengthening anteroposterior axis of the eye.
In most cases, the visual acuity of the near-sighted eye under optical correction conditions by the diffusing lenses of the corresponding diopter is increased to normal values (1.0 or 6/6 or 20/20 depending on the measurement system). Such a myopia is called uncomplicated. With complicated myopia, the visual acuity not only in the distance, but also near to the refractive error, even with a full optical correction, remains reduced. This uncorrected 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 cause of uncorrectable vision loss in myopia is most often amblyopia. It accompanies only congenital myopia of high and, rarely, of medium degree. The reason for its development is the prolonged projection onto the retina of obscure images (refractive amblyopia). Even more persistent decline in vision is noted with anisometropic or one-sided congenital myopia (anisometropic amblyopia).
Symptoms with complicated myopia (myopia)
Both congenital and acquired myopia in the case of progressive course can reach high degrees and are accompanied by complications development on 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 short-sightedness that leads to an irreversible reduction in vision and disability. The second most frequent cause of loss of vision in myopia is retinal detachment, which occurs against the background of dystrophic changes and ruptures in its peripheral parts.
In the vitreous body also there are destructive changes, increasing with the progression of myopia and playing an important role in the development of its complications. When the vitreous body is destroyed, complaints are made about floating opacities ("commas", "spiders"), with high myopia, a posterior detachment of the vitreous humor is possible, in which the patient marks a dark ring floating around the eye in a circle.
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Correction of myopia
With congenital myopia, early and correct correction is of particular importance as the main means of prevention and treatment of amblyopia. The earlier the glasses are assigned, the higher the corrected visual acuity and the less the degree of amblyopia. To detect and correct the congenital myopia is necessary in the first year of life of the child. In young children with anisometropia up to 6.0 D, correction with glasses is preferable. The difference in the strength of the glasses on the twin eyes to 5.0-6.0 diopters is easily tolerated by children. Assign glasses with a force of 1,0-2,0 D, less than the data of objective refractometry in conditions of cycloplegia. Compulsory correction of astigmatism more than 1.0 Dpt. It should be borne in mind that with congenital myopia, refraction in the first years of life may be weakened, so monitoring and appropriate correction of the correction are necessary.