The formation of visual organs begins even at the earliest stages of embryo nucleation. Already in the third week of pregnancy, at the main end of the neural tube of the fetus, eye bubbles can be seen.
The process of development of the visual organs is quite complex and lengthy, lasts throughout the entire period of gestation. The formation is far from always completed by the time of childbirth - often it captures even the first weeks of a child’s life.
Unfortunately, not everything happens the way it should be: harmful environmental conditions, hereditary defects, random abnormal phenomena lead to birth defects. One of the most common among them is a coloboma. Such a phenomenon in modern realities is quite common.
Description
Coloboma is the absence of some parts of the tissues of the 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 closure of the palpebral fissure, occurring around the 4th-5th week of fetal development.
Any parts of the visual system can be injured: from the nerve to the eyelids. Often, pathology is accompanied by microphthalmus - a sudden decrease in the parameters of the eyeball and an increase in pressure.
Traumatic coloboma - this pathology is quite rare 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 excision of the affected tissues of the eye was performed.
Varieties of anomalies
- Iris coloboma is the most common form of vice. In the case of a birth defect, the pupil, as a rule, has the shape of a drop or keyhole. At the same time, all the abilities of the eye are preserved: the muscles are functioning, it normally responds to light, so that with a small size of the defect, vision remains full. But in the case of acquired coloboma, the sphincter often stops working.
- The pathology of the choroid is the absence of a piece of choroid.
- An abnormality of the ciliary body negatively affects the functioning of the accommodation system and leads to visual impairment.
- The 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 can dry out, which provokes a corneal ulcer and other secondary diseases.
Different forms of coloboma are often found in parallel. It happens both unilateral, and bilateral.
In the case when the 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, if its location is different - atypical.
Causes of anomalies
Coloboma is a rather rare (orphan) defect, and occurs in one infant for 10 thousand. Pathology is not due to either the age of the parents or racial affiliation.
The cause of the appearance of traumatic pathology is tissue damage. But congenital coloboma can develop due to many different factors.
- Systemic anomalies of development. Iris coloboma is regularly found in syndromes of Edwards, Patau, Down, epithelial hypoplasia, basal encephalocele, partial trisomy, pathologies with the names COACH and CHARGE.
- Adverse effects on the fetus. The chance of having a baby with a coloboma is much higher in mothers who, in the early stages of pregnancy, abused alcohol, drugs or were infected with cytomegalovirus pathology.
- Genetic mutation. One of the causes of coloboma of the iris of the eye is an inherited anomaly of development inherited from parents. Such a disease is transmitted in an autosomal dominant form, in other words, for the occurrence of pathology, one copy of the injured gene is enough.
Etiology
An anomaly with an X-linked transmission is extremely rare. Her gene is transmitted from the sick father to a healthy daughter, which is obtained by the bearer. Her sons as a result may be sick with a 50% probability.
However, due to the fact that the parameters of the defect in each person are individual, the carrier of 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 the disease
Iris coloboma is a pathology that is usually visible to the naked eye, as well as eyelid defects. However, its other species may not develop so obviously, imitating similar eye diseases. But certain symptoms in the coloboma still exist.
- When injuring the iris, a cosmetic flaw 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 is significantly impaired in the dark and in bright light. A photo of an iris coloboma will tell you exactly how such a vice looks like in order to detect it in time.
- With an anomaly of the choroid, the supply of nutrients to the retina is disrupted, which leads to the appearance of a blind spot. Its parameters are completely dependent on the size of the missing piece of tissue.
- Disease of the ciliary body contributes to accommodation disorders and the occurrence of farsightedness. It is much easier for the patient to focus on objects in the distance than on those located nearby.
- If we are talking about a coloboma of the optic nerve, then here, most likely, symptoms such as strabismus and disturbance of accommodation will appear.
- The anomaly of the lens has the same symptoms as astigmatism due to the loss of the natural spherical shape by the organ.
Diagnostics
Methods for detecting coloboma depend on the variety of pathology. For example, an iris disease becomes a cosmetic defect that is noticeable even with a simple examination. But to detect abnormalities of deep tissues, a comprehensive examination is needed, which includes refractometry, ophthalmoscopy, biomicroscopy.
Coloboma treatment
The only way to eliminate the pathology is surgical intervention. It is unrealistic to eliminate tissue defect with the help of special medicines or physiotherapy.
But the operation is far from 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 minor 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 pulled together and sutured to create a pupil of a normal size.
The coloboma of the eyelid is removed in the same way. After simple surgery, all functions of the organ are stabilized.
With an anomaly of the lens, as in the case of any of its other pathologies, it is replaced with an artificial lens. In terms of quality, modern devices are in no way inferior 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 should be necessarily comprehensive.
When the dry eye syndrome appears due to coloboma, the patient needs special drops. With the development of glaucoma, it is necessary to take medications that lower intraocular pressure. In the case when the patient's vision has significantly deteriorated, the ophthalmologist should prescribe him lenses or glasses with a suitable number of diopters.
Prevention
To prevent the development of congenital malformations of the expectant mother, teratogenic substances should be abandoned first. Only this stage is already able to significantly reduce the risk of her baby having both an independent ailment and a complex of diseases. But, of course, this will not save the child from an accidental gene mutation or hereditary pathology.
Forecast
In general, the clinical picture with coloboma is favorable. In itself, the disease in no way threatens the life and health of the patient. True, other pathologies that may accompany the coloboma present a danger.