The formation of the visual organs begins at the earliest stages of embryonic development. As early as the third week of pregnancy, eye blisters can be seen at the main end of the neural tube of the fetus.
The process of development of the visual organs is quite complex and lengthy, lasts throughout the entire gestation of the baby. It is far from always that the formation is completed by the time of birth - often it captures even the first weeks of a child's life.
Unfortunately, things don't always work out the way they should: harmful environmental conditions, hereditary defects, random anomalies lead to birth defects. One of the most common among them is coloboma. Such a phenomenon in modern realities is quite common.
Description
Coloboma is the absence of some parts of the tissues of parts of the eye itself and its appendages. Most often, it occurs during the period of intrauterine formation. A common cause of coloboma is impaired palpebral closure occurring around the 4-5th week of fetal development.
Injured can be any part of the visual system: from the nerve to the eyelids. Often, the pathology is accompanied by microphthalmos - a sudden decrease in the parameters of the eyeball andincreasing pressure.
Traumatic coloboma is a rather rare pathology and not as common as a birth defect. This form of the disease is provoked by mechanical damage to the visual system. Sometimes it is a consequence of surgery, during which the affected tissues of the eye were excised.
Varieties of anomaly
- Coloboma of the iris is the most common type of defect. In the case of a congenital defect, the pupil, as a rule, has the shape of a drop or a keyhole. At the same time, all the abilities of the eye are preserved: the muscles function, it reacts normally to light, so that with a small defect, vision remains full. But in the case of an acquired coloboma, the sphincter often stops working.
- Pathology of the choroid - the absence of a piece of choroid.
- Anomaly of the ciliary body negatively affects the functioning of the accommodation system and leads to visual impairment.
- Coloboma of the optic nerve and lens is much less common than other varieties. This anomaly negatively affects vision, often leading to strabismus.
- Defect of the eyelids, as a rule, affects the lower part of the organ. If the defect has an impressive size, the eyeball may dry out, which provokes a corneal ulcer and other secondary diseases.
Different forms of coloboma often occur in parallel. It can be both one-sided and two-sided.
Whena slit-like defect of the iris and other parts of the eye is located below, closer to the nose, then the coloboma is called typical, but if its location is different, it is atypical.
Causes of the anomaly
Coloboma is a rather rare (orphan) defect, and occurs in one baby in 10 thousand. Pathology is not due to either the age of the parents or race.
Tissue damage is the cause of traumatic pathology. But congenital coloboma can develop due to many different factors.
- Systemic developmental anomalies. Iris coloboma occurs regularly in Edwards, Patau, Down syndromes, epithelial hypoplasia, basal encephalocele, partial trisomies, pathologies called COACH and CHARGE.
- Detrimental effect on the fetus. The chance of having a baby with coloboma is much higher in mothers who abused alcohol, drugs or were infected with cytomegalovirus pathology in the early stages of pregnancy.
- Genetic mutation. One of the causes of coloboma of the iris is inherited from parents or an anomaly that has appeared. Such a disease is transmitted in an autosomal dominant manner, in other words, one copy of the injured gene is enough for the occurrence of the pathology.
Etiology
Extremely rare anomaly with X-linked transmission type. Her gene is passed from a sick father to a he althy daughter, who turns out to be a carrier. Her sons may, as a result, become ill with50% probability.
However, due to the fact that the parameters of the defect are individual for each person, the carrier of a coloboma may not even be aware of the existence of a pathology. Often, a miniature notch in the eye tissues is not visible without a special examination and does not have severe symptoms.
Signs of disease
Iris coloboma is a pathology that is usually visible to the naked eye, as well as eyelid defects. However, other types of it may not develop so clearly, mimicking similar eye diseases. But coloboma still has certain symptoms.
- When the iris is injured, a cosmetic defect in the form of an altered pupil often remains the only sign of an anomaly. It is noteworthy that with a small defect, the damaged organ does not suffer at all. However, with a large pathology that captures the muscles of the pupil, the patient's vision deteriorates significantly in the dark and in bright light. A photo of an iris coloboma will tell you exactly how such a defect looks in order to detect it in time.
- When the choroid is abnormal, the supply of nutrients to the retina is disturbed, which leads to the appearance of a blind spot. Its parameters completely depend on the size of the missing tissue piece.
- Ciliary body disease contributes to accommodation disorders and the occurrence of farsightedness. It is much easier for the patient to focus on distant objects than on nearby objects.
- If we are talking about an optic nerve coloboma, then here, most likely, there will besymptoms such as strabismus and disturbance of accommodation.
- Anomaly of the lens has the same symptoms as astigmatism due to the loss of the body's natural spherical shape.
Diagnosis
Methods for detecting coloboma depend on the type of pathology. For example, an iris disease becomes a cosmetic defect that is noticeable even with a simple examination. But to detect deep tissue anomalies, a comprehensive examination is needed, which includes refractometry, ophthalmoscopy, and biomicroscopy.
Coloboma treatment
The only way to eliminate the pathology is surgery. It is unrealistic to eliminate a tissue defect with the help of special medicines or physiotherapy.
But the operation is not always necessary: with a small coloboma of the iris that does not affect the patient's vision, there is no need to expose the visual apparatus to such a complex and traumatic process.
In order for the patient not to worry about the existing cosmetic defect, you can use multi-colored lenses. And from a slight photophobia, the patient will be helped by dark glasses.
In situations where the parameters of the cleft are quite impressive, its edges are excised, and then tightened and sutured to create a pupil of normal size.
The eyelid coloboma is removed in the same way. After a simple surgical intervention, all functions of the organare stabilizing.
In case of an anomaly of the lens, as in the case of any of its other pathologies, it is replaced with an artificial lens. Modern devices are in no way inferior in quality to a natural organ.
Coloboma of the choroid and optic nerve is not amenable to therapy: it is unrealistic to restore the tissues covered by these pathologies.
If the disease is accompanied by other eye ailments, treatment must be comprehensive.
When dry eye syndrome occurs due to coloboma, the patient needs special drops. With the development of glaucoma, it is necessary to take drugs that will lower intraocular pressure. In the event that the patient's vision has deteriorated significantly, the ophthalmologist should prescribe lenses or glasses with a suitable number of diopters.
Prevention
To prevent the development of congenital malformation of the expectant mother, teratogenic substances should be abandoned first of all. Only this stage is already able to significantly reduce the risk of her baby developing both an independent illness and a complex of diseases. But, of course, this will not protect the child from random mutation of genes or hereditary pathology.
Forecast
In general, the clinical picture of coloboma is favorable. By itself, the disease in no way threatens the life and he alth of the patient. True, other pathologies that may accompany coloboma are dangerous.
