What is amblyopia in children? Causes and symptoms

Lazy eye, medically also known as amblyopia, affects about 4% of children and 2-3% of the world's population. It arises in childhood, and both diagnosis and treatment are important at this time.

From the Greek: amblys, meaning weak, and ops, meaning eye.

It has been reported that if amblyopia is neglected in childhood, later correction is not possible, perhaps a partial one at best.

We perceive the world around us with both eyes. This ability is also referred to as binocular vision, which allows us to view our surroundings in 3D.

The image from both eyes is combined in the brain into a single whole. This allows us to get all the information about space, its depth so can move around in it.

If the brain does not have information from both eyes, or is unable to connect them appropriately, the problem of space perception arises. One sees 2D. This complicates the perception of the world around and movement in it.

Vision develops after birth

The period from birth to the age of 6 is the most important for our eyesight. Eyesight matures and develops.

The newborn has so-called scotopic, or having night vision. This has been adapted to intrauterine development without light. The baby can, therefore, perceive a change in the intensity of brightness, the so-called luminance. After about two weeks, the vision improves and the child begins to perceive colours.

The child watches the windows, the shadows. They can look briefly at faces or objects. Fixation of vision with both eyes begins after about the 2nd month.

In the third month, he is already watching his hands, playing with them. They reach for objects in front of them. Facial perception already focuses on the eyes, nose and mouth, whereas before it only followed its outline.

The child has perceived the world first with one eye and then with the other. Occasional different eye movements are also noticeable. The 4th month is also important in terms of emerging binocular cooperation, i.e. of both eyes.

Both eyes fixate on viewing one object. By the 6th month, the brain is already piecing information together to form a spatial image (3D). This is aided by perception in a 180° arc.

Consequently, from the 8th month onwards, visual acuity improves. Observation of the surroundings is already smooth and fluent, without jerky movements. The child is able to follow an object with his eyes without having to move his head (central fixation).

By the first year, accommodation, fixation of vision, tracking of objects are honed. Accommodation is the ability to focus on the observed object. Adjusting to the lens at different distances.

Binocular reflexes and the fusion reflex, i.e. perceiving the world with both eyes and merging the image into a single whole, are being perfected.

At preschool age, spatial perception is already developed and binocular and fusion reflexes are further strengthened.

Amblyopia means...

It is actually the brain's inability to perceive the image coming from the retina of the eye. It can affect only one eye, but it can also affect both eyes.

It arises at the time when the eyes begin to perceive together and form a single image. The brain puts the information together into a single whole, which is also referred to as the fusion reflex.

If the image from one eye is too faint or the child is squinting, the visual centre receives different images. Double vision occurs. To prevent double vision, the brain does not link the different images together.

An abnormal image from the affected eye may be blurry, foggy, distorted.

The visual perception, the reflex from the weaker eye is omitted and works, i.e. the world around is perceived only by the healthy or better focusing eye.

The brain of the weaker eye as if switches off and does not receive signals from it.

Visual acuity in the affected eye decreases as the brain does not perceive the image from that eye sufficiently or even omits it altogether.

The consequence is a loss of spatial perception. That is, there is no 3D, but only 2D vision.

The disease is not hereditary.
For children whose parents have a higher degree of myopia or hyperopia, an early eye examination is necessary.
It is most appropriate to detect dullness in children aged 3 to 4 years.
Early diagnosis and treatment is important.
Therefore, do not neglect preventive childhood checkups and a thorough eye examination.

Myopia can be of varying degrees, with the severity determined per degree by an eye exam:

1. mild - vision 6/8 - 6/18
2. moderate - vision 6/18 - 6/60
3. severe - vision worse than 6/60

Thus, the cause of blunt vision is the perception of different images and the reception of disagreeing reflexes in the visual centre, which is in the brain, as a result of which a double image is produced. The brain tries to suppress this phenomenon.

It omits information from one eye, this further contributes to the deterioration of the visual acuity of that eye.

In most cases, the cause is not an anatomical but a functional defect of the eye. For example, strabismus, i.e. squinting or dioptric error, as well as hyperopia or astigmatism may be the cause.

Amblyopia can be of varying degrees. It can affect only one eye or both eyes.

In most cases, functional amblyopia, which is caused by inappropriate stimulation, is reported.

Another kind is organic, when the cause is some pathological disorder. For example, an abnormality in the eye or as a result of damage or injury to the eye.

Table: types of amblyopia

In addition, the literature also shows a division into organic (with anatomical disturbance of the visual organ), functional (without organic cause) and mixed (organic cause is partially present and not present).

The manifestation of myopia is a deterioration of visual acuity, but also a loss of spatial perception. A person normally sees their surroundings in 3D, spatially. In tupsightedness, the spatial arrangement is reduced to 2D only.

In childhood, it is possible to notice difficulties with the perception of space and orientation in it. The child has difficulty estimating the distance from objects, the depth of space. He bumps into the surroundings, is clumsy, stumbles.

Collective activities, games and sports are a problem for children with colour blindness.

However, amblyopia may not be noticed by the parent or child at all.

The visual abilities of the healthy eye are normal, and the child cannot describe that he does not process information from one eye. He or she does not realize this and cannot even describe the fact that he or she has a problem with spatial perception.

Therefore, if we notice the following symptoms in a child, an eye examination is necessary.

Symptoms that cannot be neglected:

• clumsiness
• bumping into objects
• falling
• shape and space recognition problem
• poor estimation of distance, depth of objects
• squinting
• tilting the head to the side
• closing one eye
• avoidance of collective life, games, sports
• the child tries to avoid covering one eye
• in severe myopia, the eye can only see at a distance of 1 metre or only outlines

Just like a child, a parent may not notice a problem with dullness. It also comes to him accidentally. In childhood, preventive check-ups are also important for this problem.

A basic eye examination is carried out as early as two years of age. However, it is best at the age of 3 and 4, when the child is already able to fully concentrate on the task at hand.

When examining vision using an optotype (a chart with letters, signs, pictures), the nurse or parent must thoroughly cover one of the child's eyes with the palm of the hand.

It should not be closed using the fingers. Even a small gap between the fingers can result in a distorted result.

The child tends to dissimulate in order not to disappoint the parent.

The eye must be covered with the palm of the hand, we must not press on it, and there can be no gap between the nose and the hand. Following the examination of the first eye, the second eye is examined. Alternatively, the eye may be covered with a harder paper.

In case of uncertainty of a thorough examination, the whole process must be repeated. Alternatively, an eye examination is necessary.

Such a distorted result may cause late detection of visual impairment, such as myopia, and prolong the start of appropriate treatment.

The course of the disease is determined by the degree of impaired visual acuity. Alternatively, other causes such as squinting may also be present.

The brain does not receive consensual information.

In the visual centre, the perception from both eyes cannot be combined. Over time, the brain adapts and the image from the weaker eye is no longer perceived. It's as if it shuts down. This prevents double vision.

He perceives the image from the surroundings only from the stronger, healthier eye. And the dull-eyed eye is not exercised and continues to weaken.

The consequence is a flat rather than a spatial perception of one's surroundings. This is compounded by the symptoms and problems mentioned above.

Note: if amblyopia is not caught and treated early, i.e. in childhood and pre-school age, it leads to permanent visual problems.

A person is not able to perform some games, sports, in adulthood occupations. The overall future quality of life will deteriorate.

Visual impairment is based on a number of characteristics and can range from normal, to blurred vision, to blindness in the affected eye. As far as the brain of the eye in question has shut down. 

The brain switches off the signal from the weaker eye, and thus it is as if blind.