Anophthalmia: when you can't see the world through your eyes

It is not by chance that the eyes are called the mirror of the soul, because they are a reflection of how we perceive the world. And we perceive it with the help of our senses, among which the paired organ of vision occupies one of the leading places. The absence of eyes (anophthalmia) is a big problem that affects the entire future life of a child born with such a developmental defect that cannot be corrected. Remaining blind from birth until the end of his difficult life, a person with anophthalmia will never know what he, his family or other people look like. In addition, the aesthetic side of such a defect raises great doubts, which is the reason for turning to surgeons.

The problem of anophthalmia

The absence of organs familiar to us in a person always causes some confusion and even uncontrollable hostility, which, mixed with pity, forms a feeling that cannot be explained in words. It is experienced by those who have had to face the misfortune of another person, and the patients themselves at a conscious age instinctively feel such a dual attitude, which is psychologically very difficult.

But anophthalmia is not only a psychological and cosmetic problem, but also a medical one, because we are talking about the head and the part of it that attracts attention first. Everything in a person's appearance should be in its place, otherwise secondary defects may occur. In the case of congenital anophthalmia, this is an incorrect, disproportionate formation of the bones of the facial skeleton, which requires early surgical intervention. However, there is no talk at all about restoring vision in the absence of the eyeball and other organs responsible for visual perception of the world.

It should be said that children with such a defect as the absence of one or both eyes (unilateral and bilateral anophthalmia) are born quite rarely. Statistics say only 3-10 cases per 100 thousand babies. At the same time, outwardly newborns do not differ from normal children with closed eyes. The absence of eyeballs can be noticed when the child opens his eyes.

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Causes anophthalmia

Based on the fact that congenital absence of eyeballs is a hereditary disease caused by a mutation of the gene responsible for the development of the visual organs, it is very difficult to determine the true causes of the disease. Parents may not even suspect that their chromosome set contains a pathological gene. Reduced size of the eyeballs, which is not considered a major physiological or cosmetic defect, already implies the presence of a recessive gene, but it is simply impossible to predict whether it will be passed on to the child from both parents.

Another thing is that congenital anophthalmia can have two forms: true, the cause of which is precisely the child receiving 2 pathological genes, and imaginary, when other factors influenced the development of the fetus's visual organs. In this case, risk factors for impaired eye development can be considered any negative impact on the fetus in the 1st trimester of pregnancy, when the rudiments of virtually all human organs and systems are formed.

Of particular danger are infections that can reach the fetus through the mother's blood, affecting its development. Women whose children were born with imaginary anophthalmia were most often diagnosed with rubella, measles, and shingles during pregnancy.

Risk factors may also include toxic effects of environmental factors on the fetus or the presence of amniotic bands (connective tissue threads stretched between the two walls of the uterus) in the uterus. In the latter case, there is compression of individual parts of the fetus's body, which may cause deformations of the facial skeleton and underdevelopment of the visual organs.

Pseudoanophthalmia rarely occurs as a separate disease. It is usually one of the symptoms of various congenital syndromes (for example, Lenz syndrome, inherited in an X-linked recessive manner).

Acquired anophthalmia is the absence of one, or less commonly both, eyeballs as a result of amputation. The cause may be trauma and severe eye infections, when the tissues have to be removed to prevent the infection from spreading to the brain. In some cases, eye removal is necessary due to the presence of a tumor.

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Pathogenesis

The unusual pathology has quite explainable causes, which, however, does not inspire optimism. The fact is that while studying the pathogenesis of anophthalmia, scientists have identified one important internal factor that influences the development of the visual organs even in the prenatal period. Such a factor is specific genes, one of which is responsible for the normal development of the visual organ, and the other for its absence.

A gene is a section of a DNA molecule that carries information about the structure of a protein from which certain cells and cellular structures are formed. That is, it is a unit of hereditary material responsible for the formation of a certain function or feature that is passed on to other generations. Thus, genetic pathologies are health disorders that are hereditary in nature.

Anophthalmia, or the absence of eyeballs, is a hereditary disease, the probability of which being passed on to the next generation is extremely low. The fact is that in genetics there is such a thing as "alleles". These are different versions of the same gene, which can be passed on to offspring with varying probability.

Chromosomes are structures that include tens and hundreds of thousands of genes, representing a kind of scheme or instruction for the functioning of the body. A human child receives 2 sets of chromosomes from its parents. One set contains 23 chromosomes. The second set is considered similar to the first, i.e. chromosomes marked with the same number are responsible for the formation of cells and functions of the same structures. It turns out that we receive from our parents not one, but two homologous (with the same functions) genes.

Receiving a double set of chromosomes, we have the opportunity to receive one of the two variants of the same gene. As a rule, one of the gene variants is stronger, i.e. it manifests itself regardless of the presence in the genome (the set of genes in a single set of chromosomes) of the other allele of this gene. Such a gene and the trait caused by it are called dominant. Receiving at least one such gene from parents, we with a high degree of probability receive this trait, and not the one that can be caused by the second allele.

Weaker genes are called recessive. In combination with a dominant allele, they rarely show their properties. Only those who received 2 recessive genes from their parents have a greater probability of getting a recessive trait.

Anophthalmia, like Wilson's disease, characterized by a disorder of copper metabolism in the body with pronounced disorders of the nervous system, liver, and digestive system, is inherited in an autosomal recessive manner, i.e. a person exhibits recessive traits received together with the corresponding genes. This outcome is more likely if a child receives 2 identical recessive variants of one gene from his parents.

Those people who receive 2 identical alleles of a gene from their parents are called homozygous. If a person's double set of chromosomes contains 2 different variants of the same gene, he or she is called heterozygous for that gene.

In genetics problems, dominant genes are usually denoted by capital letters, and recessive genes by lowercase letters. For example, if a child receives a rare recessive gene (let's denote it "a") from one parent, which causes anophthalmia (abnormal eye development), and from the other - a dominant allele of this gene (let's denote it "A"), the probability of developing anophthalmia will be very low.

In a homozygous organism that has received two recessive genes from its parents, such a probability will be 100%. But what is the probability of a child being born with anophthalmia in parents, one of whom has this disease or both of whom contain a recessive gene in their genome?

We receive a set of 2 identical genes from our parents, but their combination can be different: AA, aa, Aa. In the first case, the disease definitely does not develop, in the second - on the contrary. In heterozygotes, as geneticists have found out, only a decrease in eyeballs is observed, while the probability of receiving exactly this set of genes is 50%.

The remaining 50% of children will be homozygous, i.e. with a set of 2 identical alleles of one gene: AA or aa. It turns out that the probability of anophthalmia is 25%, i.e. the disease is diagnosed in every fourth child in the family in question.

It is clear that the absence of the pathological gene "a" in one of the parents reduces the probability of developing anophthalmia to zero. This explains the small number of newborns without eyeballs.

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Symptoms anophthalmia

We have already mentioned that congenital anophthalmia can be true or imaginary, while the external symptoms of the disease are practically the same. With the true form of the disease, the cause of which is considered to be the inheritance of pathological genes, the absence of both eyes (bilateral anophthalmia) is usually observed, because if one of the received genes carries information about the normal development of the visual organ, then the child's eyeballs will develop, but will be smaller in size.

In addition to the eyeballs, children with anophthalmos also lack other eye tissues that form our organ of vision, give it the ability to move within the orbit, and focus on near and distant objects.

False anophthalmia is characterized by the absence of only the eyeball, while the other components of the eye are present but remain underdeveloped. Both eyes may be affected with equal probability. In this case, along with bilateral absence of eyes, there are children in whom anophthalmia is observed on the right (the right eye is missing) or on the left (the left eye is missing). In this case, the absence of one eye is compensated by an increase in the visual acuity of the other.

With bilateral anophthalmia, the child remains blind for life, because the prosthesis helps to solve only the aesthetic side of the problem and correct the further development of the facial skeleton.

Externally, newborns with anophthalmia are practically no different from sleeping, normally developing children. They have eye slits on their faces, but various eyelid deformations are possible (the first, although non-specific signs of developmental pathology). The defect in the form of the absence of eyeballs becomes noticeable when the child opens his eyes.

At the same time, it is almost impossible to notice a genetic deviation on an ultrasound, which can be performed more than once during pregnancy. For parents, the birth of a baby without eyes becomes a sad surprise, while the child himself does not even suspect his defect for a long time, because in the womb he did not need vision.

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Complications and consequences

The absence of one or both eyes is a tragedy that leaves its mark on the child's further development. From a medical point of view, the only complication of a pathology that arose in the early periods of a child's life may be a violation of the formation of the facial skeleton, which makes a person's appearance even more repulsive and may affect the functioning of nearby organs.

In fact, the problem is much broader. Although modern society has noticeably changed its attitude towards people with developmental disabilities and has stopped rejecting them, many still retain some shade of hostility towards them. This cannot but affect the mental and emotional state of the patient, causing a decrease in self-esteem, negativity in response to expressions of pity, isolation, etc.

True, the appearance of a person with anophthalmos can be corrected by means of surgery. Another thing is that the surgery will not restore the child's vision, and in the absence of both eyes, cognitive activity, and therefore general psychophysical development, will noticeably lag behind the norm.

Children with anophthalmia are forced to study in special educational institutions to obtain at least a basic understanding of the world around them, learn to read and write using special methods, and acquire certain self-care skills. However, they remain visually impaired for life with a limited choice of professional activities.

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Diagnostics anophthalmia

What ultrasound diagnostics cannot do in the prenatal period, the eyes of doctors can do after the child is born, when the defect becomes visible from the side. The absence of eyeballs is difficult to hide even with closed eyelids, not to mention the fact that after birth the child is examined by doctors and the reaction of the eye to light is checked.

True, the clinical picture obtained during external examination does not provide sufficient information about the causes and forms of anophthalmia, and standard tests do not help to advance in this regard. Instrumental diagnostics come to the rescue, namely X-ray examination or computer tomography of the skull.

In true anophthalmia, in addition to the eyeballs, other tissues of the visual organ (optic nerve, chiasm, lateral geniculate body), determined histologically, and even the optic opening in the bones of the skull are absent, which indicates a complete absence of the eye rudiment. The appendages of the eyes in such newborns are preserved, but have reduced sizes, the orbit and conjunctival cavity are small.

The eyelids are usually small, often deformed, which can be seen even with the naked eye. The small size of the palpebral fissure and conjunctiva is also visually determined.

Most often, such pathology is combined with general underdevelopment of the frontal parts of the brain and disturbances in the formation of the visual parts of the nervous system. Such children are prescribed additional studies to determine the depth of the defect.

False anophthalmia is characterized by the presence of a hole and a rudimentary eye in the depth of the orbit in the form of a small seal, which is detected using echography. This once again confirms the fact that the organ of vision has formed, but stopped developing at some stage of the child's intrauterine life.

X-ray and histological studies play a major role in differential diagnostics, helping to understand the mechanism of disease development and determine its form. At the same time, the disease also needs to be differentiated from microphthalmia, i.e. underdevelopment of the eye, enophthalmia (deep eye setting) and some other developmental defects of the visual organ.

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Treatment anophthalmia

When a child is born without one or both eyes, the parents naturally ask themselves: what to do next? The child's appearance and possible complications that can be avoided can become an obstacle in his future life, affect relationships with other people, and complicate his entry into society.

In order to somehow reduce the negative consequences of anophthalmia, eye prosthetics are used in combination with the use of antiseptics that do not come into contact with the prosthesis material at an early age. The fact is that the skeleton and bones of the child's skull continue to grow even after the child is born, therefore, the earlier the prosthesis is installed, the less likely it is to cause deformations.

But the growth of the skull bones is also the reason for repeated operations, during which the existing prosthesis is replaced by another, slightly larger one. Any operation, including prosthetic ones, is a trauma for the child's body, so multiple operations are considered undesirable.

An important achievement of modern medicine is the possibility of injection treatment, which replaces prosthetics in childhood. While the child is small and his bones are growing, a non-surgical method is used - the introduction of hyaluronic acid into the orbital tissue, which prevents the abnormal development of the eye socket tissue, prevents the development of facial asymmetry in unilateral anophthalmia.

Such safe treatment is possible from the first days of a child's life. The procedure is performed in an outpatient clinic under local anesthesia, without causing the baby any particular discomfort. The prosthesis is installed later, when the period of facial skeleton growth is over.

If it is impossible to perform prosthetics at the age of over 7 years, an operation is performed to increase the eye slit (external canthotomy), after which it becomes possible to use a prosthesis or implant. Unfortunately, due to the existing risk of eyelid deformation after the operation, such surgical intervention itself can become the reason for the impossibility of prosthetics in the future.

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Prevention

True anophthalmia is considered a genetic disease, the causes of which remain a mystery (it is difficult to say why a pathological gene appears and predict its transmission to offspring). It is almost impossible to prevent such a disease, unless you carefully select a sexual partner, studying the entire anamnesis of candidates. But this should be done at the stage of pregnancy planning. Those who have already had cases of anophthalmia or microphthalmia in their family, which develops if a child has been passed on one recessive gene, are at risk.

But the development of the imaginary form of pathology can be avoided even before the child is born. Prevention consists of preventing infectious diseases (especially in the early stages of pregnancy), regular ultrasound examinations, which allow detecting strands in the uterus, and avoiding the influence of poisonous and toxic substances on the pregnant woman's body.

Acquired anophthalmia is most often the result of a person's carelessness or careless attitude towards their health. By avoiding eye injuries and promptly contacting an ophthalmologist about diseases of the organ of vision, you can preserve what we are given at birth for life, enjoying the opportunity to visually perceive the world as it really is.

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Forecast

Anophthalmia is a condition in which there is uncorrectable loss of vision. A prosthesis can create the appearance of a normal eye, giving the child a familiar appearance, but it is not possible to restore vision.

The prognosis for the development of a child with congenital anophthalmia depends on the form of the pathology (bilateral or unilateral), as well as the assistance that adults (parents, caregivers, teachers) will provide to the child. As for life in general, everything depends on concomitant diseases and developmental defects, because this pathology is often only one of the symptoms of complex health problems.