Hereditary eye diseases caused by damage to the retina. Hereditary eye diseases. Recurrent corneal erosion

Hereditary diseases of the organ of vision are a large group of genetically heterogeneous diseases with a severe course, leading to early disability.

Genetics (from the Greek "genesis" - birth, origin), put forward in the category of exact sciences, shows that heredity is due to the transfer to descendants of repeating information about all the properties of a given organism. One of the important properties of heredity is conservatism, that is, the preservation of hereditary characteristics over many generations. Molecular biology shows broad prospects for altering the hereditary nature of an organism, which makes it possible to introduce or remove certain genes. This area of ​​genetics is called "genetic engineering".

Currently, the study of new approaches based on the combined study of the clinical signs of the disease and their correlation with the results of genetic analysis is the basis for the development of promising methods for the prevention and treatment of a number of congenital and genetically determined diseases of the organ of vision. Intrafamilial and pronounced interpopulation clinical polymorphism of diseases of the visual-nerve apparatus was established, which indicates their different genetic nature.

In the monograph Khlebnikova O.V. and Dadali E.L. "Hereditary pathology of the organ of vision", published under the editorship of E.K. Ginter, published modern ideas about the etiology, clinic, diagnosis and new opportunities for the prevention of hereditary eye diseases. Based on their own data on clinical and genetic correlations, the authors developed algorithms for DNA diagnosis of the most severe forms of hereditary eye diseases, presented an atlas of the clinical forms of the latter and their index by signs, allowing practicing ophthalmologists to suggest or establish the clinical and genetic form of the disease. As a result of population epidemiological studies, the authors found that in different regions of the Russian Federation, hereditary etiology is detected in 30% of patients with eye diseases, and in the structure of blindness and low vision it ranges from 42 to 84% in various populations. According to A.M. Shamshinova (2001), in 42.3% of cases eye diseases are caused by hereditary factors. In recent years, there has been a clear trend towards an increase in the proportion of hereditary diseases in the structure of ophthalmopathology.

For practical ophthalmologists, the identification of a genetic variant is necessary not only to determine the characteristics of clinical manifestations and the course of an eye disease, but, first of all, to establish the type of inheritance, calculate the risk of having a sick child in a burdened family, and plan preventive measures aimed at preventing his birth. DNA diagnostic methods are more accurate than traditional methods, as they allow you to assess the genetic risk of developing an eye disease in the family. To date, insufficient work has been done to identify individual genetic variants using molecular genetic methods. Unfortunately, there are not enough such research centers in the country. And the existing laboratory for DNA diagnostics and the laboratory for genetic epidemiology at the Moscow State Scientific Center of the Russian Academy of Medical Sciences cannot cover a large contingent of those who need these examinations.

It is important to remember the terminology related to hereditary pathology. Gene - the basic unit of heredity, is embodied in the substance of heredity - deoxyribonucleic acid (DNA) and is a section of its molecule that is transmitted from parents to their descendants. The sizes of genes are not the same and depend on the size of the protein that encodes a given gene. There are over 20,000 genes.

Epigenetics - the science of gene activity and its change, studies everything related to DNA and affecting its structure and function. It is well known that the hereditary nature of an organism is determined by a set of genes (genome) contained in the DNA of each cell. DNA contains more than 3 billion nucleotide bases of four main types: adenine, cytosine, guanine and thymine. A large amount of DNA is stored in a relatively small volume of the cell nucleus. Each chromosome contains one strand of DNA. The sequence of bases in DNA determines the life of a person.

The cause of hereditary diseases is damage to the genes that are part of the cell - a unique biological structural unit of the body. The nucleus of each cell contains chromosomes - the material carriers of human hereditary properties, containing one giant DNA molecule and hundreds of thousands of genes that control important links in the exchange at all stages of the development of the human body. Therefore, the most direct approach to diagnosing hereditary diseases is to study the DNA of the relevant genes. Modern methods of molecular genetics make it possible to study virtually any DNA fragment of a human cell. A necessary condition for conducting DNA diagnostics is the availability of information about the location of the gene on a particular chromosome. Locus - a separate section of the chromosome responsible for the implementation of a certain hereditary trait.

Genome - a set of chromosomes containing units of heredity. Therefore, the hereditary nature of an organism is determined by the genome contained in the DNA of each cell. Through mapping, it is possible to identify the position of each gene on any chromosome relative to other genes.

The gene creates enzymes that regulate biochemical processes and ensures the vital activity of the cell. DNA methylation is an important biochemical pathway, the violation of which leads to the development of eye diseases. As a result of the most complex biochemical changes in the body under the influence of many causes (diseases, intoxication, environmental influences, low and high temperatures, ionizing radiation, etc.), a change in the structure of chromosomes and genes - mutations can occur. A mutation in a human somatic or germ cell can lead to the development of a hereditary disease: corneal dystrophy, hereditary cataract, congenital glaucoma, retinal abiotrophy, and many others.

The most important problem in the practice of counseling is to determine the type of inheritance of the disease. Three main types of inheritance have been proven: 1) autosomal recessive type - both parents are carriers of the defective gene, the pathological gene is passed from generation to generation, the incidence of the disease in men and women is the same (example: cystic fibrosis); 2) autosomal dominant type - only one of the parents can be a carrier of the gene (example: tuberculous scleritis); 3) X-linked inheritance is characterized by the following genealogical data: a sick father can pass on a pathological gene to daughters who are phenotypically healthy, but are carriers of a defective chromosome. A carrier woman can receive a pathological gene from both mother and father and passes it on to her sons (example: congenital color vision deficiency).

In the Ufa Research Institute of Eye Diseases, together with the Institute of Biochemistry and Genetics of the Ufa Scientific Center of the Russian Academy of Sciences, molecular genetic studies of certain hereditary diseases of the organ of vision have been carried out for many years.

For the first time in the Republic of Bashkortostan, the effectiveness of predicting congenital hereditary cataracts was studied, taking into account genetic factors and its surgical treatment. The linkage of the autosomal dominant congenital cataract gene with highly polymorphic microsatellite markers located within the β-crystallin gene cluster was analyzed. The genotyping of individuals of the studied pedigrees by marker loci was carried out and the genetic heterogeneity of autosomal dominant congenital cataract was studied. The possibility of prenatal diagnosis of congenital hereditary cataract based on the established linkage of the ADVC gene with microsatellite markers D22S264, TOP1P2, CRYBB2 in the region of the β-crystallin gene cluster has been proven. The lack of linkage of autosomal dominant congenital cataract with the above markers in a number of other families with this pathology indicates its genetic heterogeneity.

In the children's department of the institute, genetic studies were carried out on the problem of pigment abiotrophy (Greek bios - life, trophe - nutrition) of the retina in adults and children. Tapeto-retinal abiotrophies in children are among the poorly studied severe hereditary progressive diseases that lead to blindness at working age. The disease is inherited in an autosomal recessive manner. According to the type of inheritance, monogenic (caused by defects in one gene) and digenic (caused by defects in two genes) retinal pigment abiotrophy are distinguished.

The recurrence of this pathology in families in the 3rd-4th generation was revealed, more often manifested in children with a close relationship of their parents. Several clinical forms of retinitis pigmentosa have been identified. The degree of development of retinal pigmentation depends on the genetic type of retinitis pigmentosa and the age of the patient. Various periods of manifestation of new signs of the disease were noted - from 8-10 years to 40-55 years. With the disease, a violation of dark adaptation, a concentric narrowing of the visual fields, and night blindness are noted. Various forms of hereditary retinal degeneration are caused by the manifestation of a mutation in the rhodopsin gene. Perinatal diagnosis is assisted by molecular biological genotyping, which makes it possible to identify a large number of genes that cause this disease. However, at present, interaction between practicing ophthalmologists and specialists in the field of molecular genetics is by no means always carried out.

The Institute conducted research on hereditary open-angle glaucoma. Based on a clinical, genealogical and molecular genetic study of members of 138 families, it was found that in patients with aggravated heredity, the predominant clinical form of primary open-angle glaucoma is pseudoexfoliative glaucoma (56.8%), and in the group without aggravated heredity - pigmentary glaucoma (45.5 %). A clinical and genealogical study of families in which primary open-angle glaucoma was confirmed in several generations revealed the similarity of the clinical manifestations of the disease, and the phenomenon of anticipation was traced. As a result of molecular genetic analysis, it was found that the frequency of the Q368X mutation of the myocilin gene in the group with aggravated heredity is 1.35%, which indicates the advisability of testing it in people with a family history of the disease. Therefore, if there is a family history of primary open-angle glaucoma, its premorbid diagnosis in blood relatives is necessary.

Single-digit comparisons were made between husband and wife, parents and children. A higher correlation coefficient between parents and offspring compared with those between spouses testified to the great importance of genotypic factors in determining traits. The summation of hereditary signs and micro-features, the identification of patterns of their impact on the development of glaucoma in representatives of a particular pedigree made it possible to diagnose the disease or predisposition to it in a timely manner. Tests for susceptibility to glaucoma, as noted by R.P. Shikunova help predict the disease long before its clinical manifestations and contribute to the correct prediction of pathology in future generations.

To date, the clinical and genetic characteristics of 20 nosological forms of hereditary corneal dystrophies, represented by 35 genetic variants, have been well studied. Autosomal dominant, autosomal recessive, and X-linked recessive inheritance patterns of IRR have been described. Hereditary diseases of the cornea are represented by dystrophies of various layers of the cornea and ectasias. In recent years, cases of keratoconus have become more frequent, most of which are sporadic. Only in 6-8% of cases, the monogenic nature of the disease was established. Five clinically indistinguishable genetic variants of keratoconus have been described, and the keratoconus gene has been mapped on the chromosome. Research at the institute on the problem of inheritance of keratoconus continues.

Thus, the identification of a pathological gene and its mutations is the basis for understanding the pathogenesis of the disease, predicting the course of the process, and searching for effective therapy. Given the existence of an extensive nosological spectrum and pronounced genetic heterogeneity of hereditary diseases of the organ of vision, systematic work is needed to determine the algorithm for clinical genetic research in burdened families.

Eye diseases in children are unpleasant, dangerous, they can affect the development of the child, his self-esteem, develop complexes, reduce academic performance, limit the choice of sports and even professional activities. Therefore, it is so important to detect eye diseases in children as early as possible and start the right treatment.

To help parents, in this article, we will tell you what eye diseases are in children, give them an alphabetical list, names, a brief description, signs, as well as the age of children at which this or that disease may appear.

Note! "Before you start reading the article, find out how Albina Gurieva was able to overcome vision problems using ...

In this section, we will describe all children's eye pathologies that affect visual acuity, including myopia, hyperopia, strabismus, and others.

Amblyopia

Uneven use of one eye compared to the other (lazy eye), which results in deterioration of its visual functions. The disease is treated by turning off the frequently used eye for a while, and including it in the patient's visual activity (occlusion).

Myopia

This disease is also called myopia - a frequently observed disease in childhood. Appears at about five to eight years of age. The child begins to blur objects that are far from the eyes. As a rule, it is formed during the active growth of the eye and due to the increased load on it. Myopia is treated by wearing glasses.

retinopathy

disease in premature babies. Due to the stoppage of the normal growth of retinal vessels, they develop fibrosis, scarring of the retina, which greatly affects visual functions, with the risk of complete loss of vision.

In premature babies who have suffered retinopathy, various complications are possible (myopia, astigmatism, retinal detachment). Treatment is operative.

Spasm of accommodation

Also called false myopia. With this pathology, the ability of the accommodative (ciliary) muscle to relax is impaired, which leads to a decrease in distance visual acuity. It is observed in children of school age. It is quickly eliminated with the help of gymnastic eye exercises and drug ophthalmic therapy.

Strabismus (strabismus)

A pathology in which one or both eyes are not positioned correctly, because of this they cannot concentrate on one point at the same time. As a result, binocular vision is impaired. In newborns, there is an uncoordinated look, in three to four months the eyes should align, if this does not happen, you need to see a doctor. Older children complain of blurred vision, photosensitivity, double vision, and rapid eye fatigue. Treatment should be started at the first symptoms. It is done with glasses. If the disease is caused by damage to the nerve that controls the oculomotor muscle, its electrical stimulation is prescribed, training, in case of ineffectiveness, an operation is performed on the muscle at the age of three to five.

Infectious eye diseases

In this section of the article, we will analyze all the most common ophthalmic diseases associated with infections, including conjunctivitis, keratitis, dacryocystitis and many others.

Blepharitis

An infectious disease that can be caused by various kinds of microorganisms, as well as which can appear against the background of other chronic diseases (tonsillitis, laryngitis, anemia, digestive system disease, and others). The main signs of blepharitis are similar to many other inflammatory processes (redness of the eyelids, itching, burning, photosensitivity, increased tearing). But there are also special symptoms that depend on the type of blepharitis.

Treatment must be carried out immediately to avoid complications, with antibacterial drugs.

Dacryocystitis

This is an inflammatory process in the so-called lacrimal fossa, which occurs due to the accumulation of pathogenic bacteria in it, due to a violation of the outflow of the lacrimal fluid. There is dacryocystitis of the eye in newborns and children of different ages. Symptoms are expressed in swelling, redness and pain in the inner corner of the eye, purulent discharge appears. It is necessary to consult a specialist for the correct treatment of the disease.

It is necessary to treat infectious eye diseases in children that have different forms using medical, surgical, laser, extracorporeal methods, as prescribed by a doctor.

Barley

It is characterized by the formation of a purulent abscess on the eyelid. Accompanied by itching, burning, pain, sometimes fever. The appearance of this trouble is usually caused by bacteria such as staphylococci. This disease occurs in children at any age. At the first symptoms of swelling of the eyelids, it is necessary to apply a warm compress to the affected area and consult a doctor. Treatment is with antibiotic eye drops.

Congenital eye diseases

There are also congenital eye diseases, which include such common ones as cataracts, glaucoma, as well as lesser known ones, for example, ectropion. We will talk about them below.

Glaucoma

It has a congenital character in children, it is expressed in an increase in intraocular pressure, due to disturbances in the development of the outflow tracts of the eye fluid. Congenital is called hydrophthalmos. High pressure leads to stretching of the eyeball, atrophy of the optic nerve, clouding of the cornea, resulting in loss of vision. The treatment is aimed at normalizing the pressure inside the eye, using special eye drops. If medical treatment fails, surgery is needed.

Eyelid dermoid

Occurs during the formation of the fetus, due to improper fusion of various tissues. A dense round formation appears, which has a single or multiple state, is located on the limbus, conjunctiva, cornea. It almost always has a benign character. This disease requires treatment, as it can be a focus of infections and inflammation, as a result, suppuration and degeneration into a malignant tumor will begin. It is treated only surgically, by the method of complete removal.

Cataract

In children, this is a congenitally grayish turbidity of the lens, which prevents the eye from being permeable to light and the proper development of the visual apparatus. There are no drugs that restore transparency to the lens, so doctors recommend performing an operation to remove the cloudiness when the child reaches six months of age. In case of damage to both eyes, the second one is operated on after four months. The removed lens is replaced with artificial lenses. But not every age is suitable for this or that method.

Retinoblastoma

The formation inside the eye, which is of a malignant nature. More than fifty to sixty percent of cases of this disease are inherited. It is found in children of two or three years. If a child is born in a family with cases of illness, he must be under the constant supervision of an ophthalmologist from birth. The treatment depends on the stage of the disease, is complex, consists in the use of various modern methods (radiation, drug chemotherapy, laser coagulation, cryotherapy, thermotherapy) can save the child not only eyes, but also visual functions.

Ectropion

Eversion of the eyelids, in which the lower eyelid lags behind the eyeball and is everted outward. In children, it has a congenital character, due to a lack of skin integuments of the lower eyelid or an excess of skin on the edges of the eyelids. The complication is manifested in the form of lagophthalmos, profuse lacrimation. The main method of treatment is surgery.

entropian

Congenital disease, expressed in the inversion of the eyelid, due to excess skin or muscle fibers in the area of ​​\u200b\u200bthe eyelashes, with spasm of the circular muscle. With such a disease, a resection operation is indicated.

Children are touching and defenseless creatures. It is especially difficult when they are sick. Unfortunately, it is almost impossible to protect children from some diseases, while other diseases can be prevented. In order for children to have no consequences after illnesses, it is necessary to notice something was wrong in a timely manner and consult a doctor.

Vision problems in children

Violation of the quality of vision is one of the reasons for the delay in the development of children in the first years of life. If vision is impaired in preschoolers, they cannot properly prepare for school, their range of interests is limited. Schoolchildren with low vision are associated with a decrease in academic performance and self-esteem, limited ability to engage in their favorite sport, choose a profession.

The visual system of the child is at the stage of formation. It is very flexible and has huge reserve capabilities. Many diseases of the organs of vision are successfully treated in childhood, if they are diagnosed in a timely manner. Unfortunately, treatment that is started later may not give good results.

Eye diseases in newborns

Many visual impairments develop as a result of congenital diseases. They appear immediately after birth. After treatment, children develop better, their range of interests expands.

In newborn children, ophthalmologists diagnose the following diseases of the organ of vision:

• Congenital. This clouding, which is manifested by a decrease in visual acuity and a grayish glow. Due to the violation of the transparency of the lens, light rays cannot fully penetrate into. For this reason, the cloudy lens must be removed. After surgery, the child will need or special glasses.
• Congenital - a disease of the organ of vision, in which intraocular pressure rises. This is due to a violation of the development of the ways in which the outflow occurs. Intraocular hypertension causes stretching of the membranes of the eyeball, an increase in its diameter and clouding of the cornea. There is compression and atrophy of the optic nerve, which is the cause of the gradual loss of vision. With this disease, eye drops that reduce intraocular pressure are constantly instilled into the conjunctival sac. If conservative treatment fails, surgery is performed.
• Retinopathy of the newborn is a disease of the retina that develops mainly in premature babies. With this pathology, the normal growth of retinal vessels stops. They are replaced by pathological veins and arteries. Fibrous tissue develops in the retina, followed by scarring. Over time, retinal occurs. At the same time, the quality of vision is disturbed, sometimes the child stops seeing. Treatment of the disease is carried out with the help of laser therapy, if it is ineffective, an operation is performed.
• - this is a condition in which one or both eyes look in different directions, that is, they deviate from a common fixation point. Until the fourth month of life, the nerves that control the oculomotor muscles are not formed in children. For this reason, the eyes may deviate to the side. In the case when strabismus is strongly expressed, consultation of an ophthalmologist is necessary. In children, spatial perception may be disturbed, develop. In order to correct strabismus, it is necessary to eliminate the cause of the disease. To do this, children are prescribed special exercises to train weakened muscles, perform vision correction.
• represents involuntary movements of the eyeballs either in a horizontal position or in a vertical position. They can turn around. The child is not able to fix his gaze, he does not develop high-quality vision. The treatment of this disease is to correct visual impairment.
• Ptosis is the drooping of the upper, which occurs due to the underdevelopment of the muscle that lifts it. The disease can develop due to damage to the nerve that innervates this muscle. When the eyelid is lowered, little light enters the eye. You can try to fix the eyelid with adhesive tape, but in most cases, children aged 3 to 7 years undergo surgical correction of ptosis.

Visual impairments in preschool children

Strabismus

One of the diseases that lead to a violation of the quality of vision in preschool children is strabismus. This pathology can be caused by such reasons:

• uncorrected violation;
• decreased visual acuity in one eye;
• damage to the nerves responsible for the work of the oculomotor muscles.

In the presence of strabismus, the image of the object does not fall on the same parts of the eyes. In order to get a three-dimensional picture, the child cannot combine them. In order to eliminate double vision, the brain removes one eye from visual work. The eyeball, which is not involved in the process of perceiving an object, deviates to the side. Thus, either convergent strabismus is formed, towards the bridge of the nose, or divergent - towards the temples.

Treatment of strabismus is recommended to start as early as possible. Patients are prescribed glasses that not only improve the quality of vision, but also give the eyes the correct position. With damage to the oculomotor nerves, electrical stimulation is used and exercises are prescribed to train a weakened muscle. If such treatment is ineffective, the correct position of the eyes is restored surgically. The operation is performed on children aged 3-5 years.

If one eye is tilted to the side or sees worse, amblyopia develops. Over time, visual acuity in the unused eye decreases. For the treatment of amblyopia, the healthy eye is switched off from the visual process and the affected organ of vision is trained.

Refractive pathology

In preschool children, such refractive errors are often diagnosed:

• . It is most common in children 3 to 5 years of age. If hypermetropia reaches 3.5 diopters in one eye, and there is a different visual acuity in both eyes, amblyopia and strabismus may develop. Children are prescribed glasses to correct vision.
• When the child does not see well into the distance. His visual system is unable to adapt to such an anomaly, therefore, even with a slight degree of myopia, children are prescribed spectacle correction.
• In the case, the image of objects that are located both near and at a far distance is distorted. With this pathology, a correction is prescribed with complex glasses with cylindrical glasses.

Eye diseases in schoolchildren

School-age children are also susceptible to refractive errors.

Myopia

With this violation of visual function, the size of the eyeball increases or light rays are excessively refracted. They converge in front of the retina, and a fuzzy image is formed on it. Due to the active growth of the eyeball and increased load on the apparatus, children aged 8-14 develop myopia. The child cannot see what is written on the blackboard where the ball is while playing football. To correct myopia, children are prescribed glasses with diverging lenses.

farsightedness

Farsightedness, or hyperopia, is a refractive error that occurs due to the small size of the eyeball or insufficient refraction of light rays. In this case, they converge at an imaginary point located behind the retina. It forms a fuzzy image. Most often, farsightedness is first detected in children of ten years of age. If hypermetropia is low, then the child sees objects located far away well. Due to the good accommodative function, he clearly sees objects located at a short distance. Glasses are prescribed to schoolchildren in the presence of such indications:

• hyperopia above 3.5 diopters;
• deterioration in visual acuity of one eye;
• appearance when working at close range;
• the presence of headaches;
• eye fatigue.

To correct hypermetropia, children are prescribed glasses with converging lenses.

Astigmatism

Astigmatism is a visual impairment in which light rays refract differently in two mutually perpendicular planes. As a result, a distorted image is formed on the retina. The cause of astigmatism may be uneven curvature, formed as a result of a congenital anomaly of the eyeball. If the difference in refractive power does not exceed 1.0 diopter, then it is easily tolerated. In the case when the astigmatism is of a higher degree, the contours of objects that are at different distances are not clearly visible. They are perceived as distorted. The difference in refractive power is compensated by complex glasses with cylindrical glasses.

With an accommodation disorder, the clarity of perception is lost when considering those objects that are at different distances or move relative to the observer. It develops due to a violation of the contractility of the ciliary muscle. In this case, the curvature of the lens remains unchanged. It provides clear vision only at a distance or near.

In children aged 8 to 14 years, as a result of excessive stress on the eyes occurs. The ciliary muscle contracts and loses its ability to relax. The lens becomes convex. It provides good near vision. In this case, students have trouble seeing into the distance. This condition is also called false myopia. With a spasm of accommodation, children perform gymnastic exercises for the eyes, they are prescribed instillations of special drops.

Lack of convergence is manifested by a violation of the ability to direct and hold the visual axes of both eyeballs on an object that is at a close distance or moves towards the eye. In this case, one or both eyeballs deviate to the side, which causes double vision. Convergence can be improved with specific exercises.

If the patient does not have the opportunity to combine the two images that are formed on the retina of the left and right eyes in order to obtain a three-dimensional image, a disorder of binocular vision develops. This happens due to differences in the clarity or size of the images, as well as when they hit different parts of the retinas. In this case, the patient sees two images at the same time, which are shifted one relative to the other. In order to eliminate diplopia, the brain can suppress the image that is formed on the retina of one eye. In this case, vision becomes monocular. In order to restore binocular vision, it is necessary, first of all, to correct violations of visual function. The result is achieved as a result of prolonged training of the joint work of both eyes.

What else can be done to restore vision in a child?

With refractive disorders in children (myopia, hypermetropia and astigmatism), as well as strabismus and amblyopia, most ophthalmologists prescribe courses of hardware treatment that give a good effect. If earlier, for this, young patients and their parents needed to visit the clinic, spending time on the road and queues (and sometimes nerves and money), now, with the development of technology, a number of effective and safe devices have appeared that can be used at home. The devices are small, affordable and easy to use.

The most popular and effective devices for home use

Glasses Sidorenko (AMVO-01)- the most advanced device for independent use by the patient in various eye diseases. Combines color impulse therapy and vacuum massage. It can be used both in children (from 3 years old) and in elderly patients.

Vizulon- a modern device for color-impulse therapy, with several programs, which allows it to be used not only for the prevention and complex treatment of visual diseases, but also for the pathology of the nervous system (for migraine, insomnia, etc.). Supplied in several colors.

The most famous and popular device for the eyes, based on the methods of color pulse therapy. It has been produced for about 10 years and is well known to both patients and doctors. It is low cost and easy to use.

Many parents with eye problems worry that their children will develop vision problems as well. Some eye diseases are actually hereditary, but sometimes they can be prevented. This article will discuss the types of hereditary eye diseases and the causes of their occurrence.

If we turn to statistics, we can see that almost ten percent of all diseases are inherited at the genetic level. As mentioned above, this also includes diseases. Many of them are asymptomatic and do not affect visual acuity, so not in all cases it can even be suspected that a person has any problems in the visual system.

Causes of congenital eye diseases

It is worth noting that the main cause of pathologies of the organs of vision is a gene mutation that provokes the development of hereditary eye diseases. What other reasons provoke the appearance of eye diseases in a child? So, among the main reasons are:

1. Pathologies of tissue development during pregnancy;
2. Hormonal disorders;
3. Incompatibility of Rh factors of mother and fetus;
4. The age of the parents (most often, organ pathologies occur in the children of those parents who decide to have a child before the age of 16 or after 40);
5. Chromosome mutations;
6. Difficult or pathological childbirth;
7. Incest, which often leads to the development of fetal anomalies.
8. Influence of environmental factors, among which are: radiation, infectious and viral diseases suffered during pregnancy, alcohol abuse and smoking of the expectant mother, etc.

What eye diseases are inherited

Here it is worth noting right away that hereditary eye diseases are divided into three large groups:

1. Congenital pathologies (in this case, surgical treatment is prescribed);
2. Small defects (as a rule, they do not require special treatment);
3. Anomalies of the eyes associated with diseases of other organs.

List of major eye diseases that are inherited:

1. Color blindness (a person does not distinguish colors);
2. Microphthalmos (disproportionately small in humans);
3. Anophthalmos (absence of one or two eyeballs);

4. Anomalies of the cornea - for example, a change in its shape (keratoconus) or its congenital clouding.
5. Glaucoma (increased intraocular pressure);
6. Cataract (clouding of the lens of the eye);
7. Anomalies in the structure of the eyelids.
8. Myopia (myopia) is an eye disease in which a person sees poorly in the distance, but sees well near.
9. Nystagmus (involuntary movements of the eyeballs).

If future parents have any eye diseases, they should consult a geneticist for advice. The specialist will tell you what preventive and therapeutic measures parents will need to take.

Patients and families apply for genetic counseling to get information about the nature of the disease, the risk of developing the disease or passing it on to children, about the problems of genetic testing, childbirth and treatment. Genetic counseling aims to help patients understand the information received, choose the best course of action and best adapt to the disease.

Accurate diagnostics- the main condition for effective genetic counseling. Diagnosis of many hereditary eye diseases is carried out on the basis of clinical data, this requires the participation of specialist clinicians and, often, a multidisciplinary approach, with genetic, ophthalmological and electrophysiological studies.

Diagnosis is based on a detailed family history with a 3-generation family tree, physical examination (often several family members), and anamnesis of the disease, including a description of systemic manifestations. It is extremely important to be alert for ocular and extraocular manifestations of the disease.

genetic counseling in hereditary diseases of the eye can be a particularly difficult task. Heterogeneity and overlapping phenotypes make it difficult for patients to understand the diagnosis. Many hereditary retinal diseases are accompanied by a progressive deterioration of vision and require prior adaptation to the need for care. The communication needs of visually impaired patients require that information be provided to them in an appropriate format.

a) Genetic laboratory tests. Molecular analysis has become cheaper and more accessible; it is currently applicable in the clinic. The clinician needs to be aware of its possibilities. For monogenic inherited eye diseases, the analysis will likely consist of gene sequencing. Analyzes are performed as a complementary method to a detailed clinical examination. They are carried out in order to clarify the diagnosis, for example, in diseases characterized by extreme genetic heterogeneity, indistinguishable clinically.

In future genetic diagnosis may be required for gene-specific treatment (drug or gene therapy). If risk assessment, for example, in a disease with dominant inheritance, does not cause difficulties, then for relatives of a patient with a dominant phenotype with reduced penetrance (dominant optic atrophy and autosomal dominant congenital cataract) or children of women from a family where men suffer from X-linked retinoschisis is more complex.

Molecular analysis in progress based on DNA isolated from the peripheral blood or saliva of one sick patient (proband) or a wider range of relatives. Once a pathogenic mutation has been identified, other family members can be screened, incl. unborn, for its presence.

b) What is a mutation? Genetic variation is the result of the DNA mutation process. Various mechanisms of mutations in hereditary genetic and Mendelian human diseases have been described. Most of them are an all-or-nothing phenomenon: sick patients are carriers of pathogenic genetic changes ("mutations"), while healthy individuals are not. In such cases, sick members of this family are carriers of the same genetic changes, and these changes do not change.

However, there is a small group of diseases, which include, for example, myotonic dystrophy, characterized by "dynamic" mutations, in which genetic changes in different generations of the same family can vary.

1. Chromosomal alterations. The most gross genetic changes are alterations at the chromosome level, namely, cytogenetically visualized rearrangements, such as deletions, inversions, duplications and translocations. Such a "genomic imbalance" is very poorly tolerated, and over the entire period of ongoing research, only an insignificant part of all possible rearrangements was observed. Such changes include trisomies (eg, trisomy 21 or Down's syndrome) as well as large chromosomal deletions (eg, 11p chromosome deletion causing WAGR syndrome, see above).

2. Submicroscopic genomic rearrangements. It is now possible to compare subtle differences in the number of DNA copies between different individuals. "Submicroscopic genomic rearrangements" include both the loss of genetic material (microdeletions) and an increase in its amount (microduplications) and are the causes of human hereditary diseases. For example, submicroscopic deletions of the X chromosome have been described in choroideremia, xLRP, and Norrie's disease.

3. monogenic mutations. Many hereditary eye diseases develop as a result of pathological changes in any one gene. The best described single base substitution mutations are also referred to as "point mutations". The Cardiff Human Gene Mutation Database is an online repository of information on identified human gene mutations. Pathogenic point mutations can lead to the substitution of one encoded amino acid for another (missense mutations). If these changes cause a malfunction of the protein, it leads to disease.

A change in one base that results in to form a stop codon from a codon, which normally codes for an amino acid, is called a nonsense mutation. Most nonsense mutations cause a reduction in the amount of protein produced during translation.

After transcription from immature mRNA molecule during splicing, extra sections are cut out, and mature mRNA is formed. Splicing is a complex process during which a huge protein complex (spliceosome) interacts with mRNA molecules. There are a huge number of mutations - especially those localized at or near the junction between exons and introns - that cause interruption of the splicing process (splicing mutations).

Others often common DNA mutations that cause monogenic human diseases are small deletions / insertions, in which up to 20 base pairs of DNA are lost or inserted. Insertion/deletion mutations less than three bases in length cause a gene frameshift and the formation of a premature terminal codon. Most of these mutations result in mRNA from which the polypeptide is not translated.

in) DNA sequencing. It is believed that in diseases transmitted according to the laws of Mendel, most patients are carriers of one pathogenic DNA change (mutation). Most of these mutations are within or near the coding sequences of genes, the list of which is growing.

1. Traditional DNA sequencing. Until recently, DNA sequencing was performed according to the traditional method. For this, amplification of short fragments of each gene (possibly 300-500 base pairs) was carried out using polymerase chain reaction. Therefore, the process of sequencing small genes is simpler and cheaper than large genes. It takes ten times longer to study ten genes of the same size than to analyze one gene. This work is expensive and time consuming. In some situations, the results of gene analysis determine the tactics of further management of the patient.

At xLRP Most patients have mutations in one of the two genes (RP2 and RPGR), so the traditional sequencing technique using modern technologies is quite simple and informative for practical use. This is also true for stromal corneal dystrophies caused by mutations in the TGFBI gene on chromosome 5q31, since the number of mutations that cause Bowman's membrane dystrophies (Thiel-Behnke and Reiss-Buckler), as well as granular and lattice type I, is very small.

But mutation analysis can be difficult even if the disease is caused by mutations in a single gene. For example, laboratory diagnosis in Cohen's syndrome and Alström's syndrome is very difficult due to the size and complexity of the genes whose mutations cause these diseases. In the case of ABCA4 (its mutation causes Stargardt's disease), which contains 51 exons and 6000-7000 base pairs of DNA, gene sequencing becomes an incredibly time-consuming task. In addition, the sensitivity of the method for detecting mutations, including known ABCA4 mutations, is well below 100%. As a result, the value of a negative result is greatly reduced.

Finally, for some genes, including ABCA4, in the norm, a high degree of variability is characteristic, both for the gene and for the encoded protein. The answer to the question of whether a single amino acid substitution variation is pathogenic remains a difficult task.

2. High Efficiency DNA Sequencing. In genetically heterogeneous diseases (e.g., congenital cataract, neuroopticopathy, arRP, Usher syndrome), when mutations of a huge number of genes are possible and there is no predominance of a mutation in any one gene, the diagnostic strategy based on traditional DNA sequencing is of little use. Some success has been achieved with the advent of DNA chips that allow the identification of previously described mutations (eg, Leber's congenital amaurosis, Stargardt's disease), but these techniques are applicable mainly in a previously examined population and their value is limited.

massive parallel DNA sequencing, also called next-generation sequencing, is likely to change that. These developments make it possible to sequence the entire human genome, provide the ability to analyze all exons of all genes or any part of them in any patient. With the help of these technological developments, it has already been possible to significantly accelerate the process of identifying unknown genes whose mutations cause human diseases. With the price coming down (sequencing the entire human genome is predicted to cost as little as $1,000 in the not-too-distant future), there is a real possibility that large-scale genetic research will become a reality.

These studies will require a decision Problems storage of a huge amount of data, since such systems give out gigantic amounts of information. In addition, since many of the anomalies that cause diseases of the human eye are missense disorders, and since a huge number of our genes normally have differences manifested in the substitution of one amino acid for another, the problem arises of identifying one pathogen from a huge variety of benign variants, a carrier which each individual is.

G) Genetic Analysis: Counseling and Ethical Aspects. Genetic analysis is becoming more and more accessible. Families and clinicians can use genetic analysis to confirm the diagnosis and type of inheritance, and possibly participate in gene-specific therapy trials in the future. Genetic analysis can have significant and far-reaching implications for the individual and his family. A patient who intends to undergo a genetic examination may need to think about how he will inform his relatives, incl. further, how the results of the analysis will affect his decision to have children and other life-determining decisions, and related issues, such as health insurance and life insurance. When referring for genetic analysis, counseling and informed consent are of great importance.

1. Prognostic or presymptomatic examination. In late-onset diseases for which the gene responsible for their development is known (eg, TIMP3 and Sorsby's fundus dystrophy), clinically healthy individuals at a 50% risk may agree to undergo genetic testing and find out if they are carriers. For late-onset genetic diseases, such as Huntington's disease and cancer predisposition syndromes, quality counseling protocols are important, taking into account the pros and cons of the study, the impact of its results on the patient and his life-determining decisions, psychological support in adapting to the results and other aspects, such as insurance.

The principles of management of patients who become aware of their diagnosis of incurable progressive visual loss, which will affect their life choices, dependency on care and emotional state, are the same.

2. Media Examination. In recessive X-linked diseases, once a patient has a genetic mutation, other members may agree to be tested for carriage. In consanguineous marriages, spouses will be able to find out if they are a pair of carriers. Women may agree to be tested for X-linked diseases in order to decide whether to have children, perform prenatal examinations, or to be more aware and prepared for the development of the disease in future sons. The implications of this information for the couple and the support that may be needed after the survey has been completed should be considered as elements of the survey process.

3. Examination of children. Indications for examination may arise in childhood-onset diseases, when the results of the analysis will affect the management of the patient or the decision on assistance in upbringing / education. However, careful counseling and preparation of parents for such decisions is of great importance, since information about genetic status and risks can greatly influence the process of raising a child. For diseases that may not become clinically apparent until adulthood, it is usually recommended to wait until the patient is old enough to make decisions for themselves.

4. Prenatal examination. If there is a known genetic mutation in the family, the spouses have the opportunity to conduct prenatal diagnosis. Chorionic villus sampling (at 11 weeks) and amniocentesis (at 16 weeks) allow accurate genetic diagnosis. Because these tests are invasive, there is a small risk of miscarriage.

Attention needs to be paid to the reasons that motivate individuals to be tested. The decision to terminate or keep the pregnancy in case of positive results of the study is made individually based on personal experience, resistance to stress (coping strategies) and available support. Although prenatal examination is rarely performed for late onset eye diseases, in families with early onset blindness or syndromes of multiple congenital anomalies, such as Lowe's and Norrie's diseases, prenatal diagnosis is advisable, and if pathology is detected, termination of pregnancy is advisable.

Pre-implantation genetic diagnosis involves the examination of embryos during IVF before implantation in the uterus. Such research is becoming available in several genetic diseases of the eye, but it poses new ethical issues that will have to be addressed in counseling.

e) Clinical examination. Clinical examination can be as important as genetic laboratory analysis. Asymptomatic individuals may present with minor eye changes indicative of their genetic status. Therefore, the ophthalmologist should be prepared to inform and counsel the patient prior to conducting an examination for hereditary eye diseases, so that the patient is informed and prepared in case of detection of genetic abnormalities.