Astigmatism, or irregular cornea shape, is a fairly common eye condition in both adults and children.
But only 30-40% of affected children have the disease detected in time. How crucial may it be?
What is astigmatism?
The cornea is the most anterior part of the eyeball, located in front of the pupil. It has a slightly oval shape and is spherically convex according to the shape of the eyeball. If this sphericity is not uniform, specialists call it a curvature of the cornea, or astigmatism. The word itself is of Greek origin and means "lack of points."
When the cornea is irregularly spherical, the rays of light entering the eye are unable to focus at one point of the retina (this physiological mechanism ensures visual acuity).
When there is a curvature in different parts of the cornea, the light rays are formed into beams in different ways. As a consequence, they get together on the retina not at one point, but in a line, which leads to a blurred image.
Although the disease is most often associated with corneal sphericity disorder, it also has a broader meaning. It can also occur as a result of irregularities in the lens of the eye and even the fundus of the eye. That is, astigmatism is also possible with a regular shape of the cornea.
Types of disorder
Specialists distinguish different forms of this pathology and, depending on this, choose one or another method of treatment.
With regular astigmatism, the cornea is not uniformly spherically curved, but "distorted". There is a shift in the focal lines, which causes distortion of vision. If the curvature is slight, the brain compensates for this visual defect. A more pronounced curvature leads to myopia or hyperopia. In the first case, a focal line appears in front of the retina, so close objects are seen sharply, and distant objects are blurred. In hyperopia, the opposite is true: the focal line is behind the retina. Near objects become blurred.
Irregular astigmatism often occurs as a result of trauma to the eye. In this severe form of the disease, the cornea is not flat and smooth, but very irregularly curved. Because of these "indentations" in the cornea, incident light is refracted in different directions.
Causes of refractive error
The issue can have many causes, and, moreover, it can appear at any age, for example, in a 2-year-old child or, conversely, in an elderly person.
Astigmatism and associated myopia or hyperopia can be caused by external influences, but can also be genetic.
It has been proved by research that the presence of the disorder in parents and/or grandparents is a factor of increased risk of its development in their offsprings. And the higher the degree of their disease, the greater the likelihood of its development in offsprings.
Therefore, if someone in the child's family suffers from astigmatism, he should be shown to an ophthalmologist as early as possible to rule out the presence of a visual defect.
External factors include trauma or disease, among others:
- The upper eyelid puts too much pressure on the eye, which can cause the cornea to warp unevenly.
- The cornea has become cloudy, for example, due to cataract.
- There are scars on the cornea as a result of surgeries and diseases.
How can irregular shape of the cornea affect a child's health?
If the disease is not identified in time, it means that appropriate treatment is not administered. This can lead to consequences of varying degrees of severity. For example, inhibition of the development process, frequent headaches and other health problems.
In some cases, the brain manages "to beat" astigmatism and forms a clear picture of vision even with uneven visual acuity. In other cases, the eye can not learn to see correctly, and later, even with special corrections, the brain is unable to do so.
With unequal visual acuity, it is also possible that the brain will gradually "delete" the signal of the weaker eye, up to its disconnection. This process is reversible and correctable only up to the age of 12, then not.
All this makes the issue of childhood astigmatism not so harmless and requires timely action.
How can you suspect that your child has astigmatism?
If the defect is present only to a small degree, it usually does not adversely affect either vision or development. However, starting with a curvature of 0.5 diopters, the visual defect becomes noticeable.
Children in their first years of life are unable to report that they can't see very well. A little person with impaired vision, does not know another world, so they do not realize that what the picture they see is blurred.
Parents can detect signs of possible disorder in babies by observing them in everyday life.
There is a chance that as the child grows, this condition will cause problems with learning at school. Lack of attention and even hyperactivity should be considered as signs. Inability to concentrate during the learning process may be due to the fact that the letters in textbooks, as well as on the school blackboard, are not focused by the child's eye. The disease may also be indicated by complaints of frequent headaches, especially in the eye and forehead areas. In addition, such children often tilt their head to look at something. One of the symptoms could be frequent redness and itching of the eyes, because during the school day the eyes of the child strain too much.
When reading aloud, these children sometimes skip whole lines or transpose syllables in the words they are reading.
It is very important that if the parents (or one of them) have astigmatism, or it is present in the grandparents, they do not miss possible signs of this disorder in their child and timely visit an eye specialist for early diagnosis. Performing a visual test to evaluate the visual function helps in the early diagnosis of the disease. The doctor clarifies the degree and form of the disease with the help of additional tests. Depending on the results of the examination, clinical features, and the age of the child, the appropriate type of treatment is chosen. Its timely and consistent implementation contributes to the preservation of vision and helps avoid complications.
Children with astigmatism at an early age should be regularly examined by an ophthalmologist. This allows the disorder to be detected and treated in time, so that the child's vision develops according to age.
Astigmatism treatment in children
Although childhood astigmatism cannot be eliminated, it can be effectively managed. With the help of appropriate therapy, it is possible not only to correct the visual defect (farsightedness or nearsightedness), but also to create a basis for the healthy development. There are several methods to treat corneal irregularities in children.
Eyeglasses: if the shape is correct, so-called cylindrical lenses are used. These are specially curved spectacle or contact lenses that refract the incident light in such a way that the curvature of the cornea is equalized, providing a good therapeutic effect.
If a child with astigmatism has already developed amblyopia due to different visual acuity of the eyes, occlusion therapy can compensate for this. A patch is applied to the stronger eye. This stimulates the brain to focus on the information coming into the weaker eye and trains its visual acuity.
Contact lenses are used to compensate for correct astigmatism, and for irregular astigmatism they are the only therapy option. By creating a tear film under the lens that fills in the irregularities of the cornea, lenses ensure the correct refraction of light.
Surgical procedure (refractive surgery) is often performed with a laser that removes excessively curved areas of the cornea. As a result, the surface becomes spherical again and there is no need to wear vision aids.
Add-on lens implantation (AddOn) is another surgical procedure that corrects refractive anomalies caused by corneal curvature.
Can astigmatism in a child clear up on its own with age?
Although the condition may change, it is unlikely that the issue will disappear completely over time. In extremely cases the degree of deformity may be slightly reduced. But more often astigmatism is accompanied by other vision problems, as well as complaints such as chronic headaches. Therefore, your child should be seen regularly by an ophthalmologist - even if he or she already wears glasses - so that any deterioration can be quickly recognized and corrected.
References:
- Astigmatismusrisiko beim Kind von StΓ€rke des elterlichen Astigmatismus abhΓ€ngig. Deutsches Aerzteblatt, Freitag, 30. Dezember 2022 www.aerzteblatt.de
- Jane Gwiazda, Kenneth Grice, Richard Held, James McLellan, FrankThorn. Astigmatism and the development of myopia in children. Vision Research, Volume 40, Issue 8, April 2000, Pages 1019-1026
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