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Congenital cataract: birth defect of the eye that lens become cloudy instead of clear

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Congenital cataract is a partial or complete clouding of the lens of the eye that develops in utero. It manifests itself to varying degrees from the moment the child is born: from a barely noticeable whitish spot to a completely affected lens. Congenital cataract is characterized by a decrease in vision or complete loss, and strabismus and nystagmus are also noted in children. Primary diagnosis is carried out prenatally; after birth, the diagnosis is confirmed by ophthalmoscopy and slit biomicroscopy. Surgical treatment is shown; lensvitrectomy is performed in the first months of life in uncomplicated cases.

 

General information

Congenital cataract is a pathology of the organ of vision, often found in the clinic of many childhood diseases. In 36% of cases, it occurs due to intrauterine infections. The general frequency of congenital cataracts in the population is 1-9 cases per 10,000 newborns. The share of this disease among all defects of the organ of vision is 60%. No gender differences in incidence were found, with the exception of genetic mutations that are more common in boys, while girls often remain asymptomatic carriers of the altered gene. Currently, the problem of congenital cataracts in pediatrics is given special attention. The disease is caused by many reasons, so the efforts of doctors are aimed at the prevention and early diagnosis of cataracts. Improving methods of surgical treatment. All measures are aimed at preserving the child’s vision for better social adaptation.

 

Causes of congenital cataract

Most often, congenital cataract accompanies a group of TORCH infections, which includes rubella , toxoplasmosis , herpes virus, and cytomegalovirus infection . However, it is not the only symptom. Each disease has its own specific symptoms. The second most common cause of congenital cataracts is metabolic disorders in a child: galactosemia , Wilson’s disease , hypocalcemia, diabetes mellitus and others. Occasionally, the disease occurs in connection with genetic mutations in the autosomal dominant and autosomal recessive types. Mutations linked to the X chromosome are even rarer.

In the case of chromosomal pathologies ( Down’s syndrome , cat’s cry syndrome , punctate chondrodysplasia , Hallermann-Streiff-Francois syndrome, etc.), congenital cataract is also not the only symptom. As a rule, it is accompanied by disorders of physical and mental development and other manifestations specific to a particular nosology. Exogenously acting causes of the disease can be antibiotic therapy of a pregnant woman, steroid hormone therapy, radiation therapy and the influence of other teratogenic factors. Separately isolated congenital cataract of prematurity .

Opacification of the lens occurs by one of two mechanisms. Firstly, initially incorrect laying of the organ of vision. It is typical for intrauterine infections in the early stages of pregnancy, chromosomal pathologies, and in general any teratogenic effect if it occurs in the first weeks of pregnancy when the organ system of vision is formed in the fetus. The second mechanism is the defeat of the already-formed lens. It often occurs with metabolic disorders (galactosemia, diabetes mellitus, etc.), and exposure to external damaging factors during pregnancy (second or third trimester). In any case, the structure of the lens protein changes, due to which it gradually becomes hydrated and then loses its transparency, as a result of which a congenital cataract develops.

 

Classification of congenital cataract

The disease is divided into types depending on the location of the turbidity zone and its vastness. There are the following types of cataracts: capsular, polar (anterior and posterior), layered (membraneous), nuclear, complete.

Capsular congenital cataract is a decrease in the transparency of the anterior or posterior lens capsule. The lens itself is not affected. Visual impairment is often minor, but blindness also occurs if the damage to the capsule is extensive, or both the anterior and posterior capsules are affected at the same time.

With a polar cataract, changes affect the anterior or posterior surface of the lens. The capsule is most often also involved in the process. This species is characterized by bilateral lesions. The degree of visual impairment varies greatly.

A stratified cataract is a clouding of one or more of the central layers of the lens. The most common type of congenital cataract is usually bilateral. Vision is usually significantly reduced.

Nuclear cataract is called clouding of the central part of the lens – its nucleus. This variety occurs in all hereditary causes of the disease. The lesion is bilateral, vision is reduced up to complete blindness.

A complete congenital cataract is characterized by clouding of the entire lens. The degree of clouding varies, but more often this form of the disease completely deprives the child of vision. The defeat is bilateral.

By origin, congenital cataract is divided into hereditary and intrauterine. The first of them is transmitted to the child from one of the parents, the second develops in the fetus directly during pregnancy. Atypical (polymorphic) is considered a cataract of complex shape. There are unilateral and bilateral cataracts, and the disease is also classified according to the degree of visual impairment (I-III degrees are distinguished). Some classifications separately designate a complicated form of cataract, but this can be called any clouding of the lens, accompanied by diseases of other organs.

Symptoms of congenital cataract

The main symptom is clouding of the lens of one degree or another. In the clinical picture, it may appear as a noticeable white spot against the background of the iris, but more often there are cases of congenital cataracts when this symptom is absent. With a unilateral lesion, strabismus is noted , as a rule, converging . Sometimes, instead of it, pathological rhythmic trembling of the eyeball is found. Almost all children with bilateral congenital cataracts have nystagmus . At about two months of age, healthy children can already follow the object with their eyes, but this does not happen in case of illness, or the baby always turns towards the object only with a healthy eye.

Diagnosis of congenital cataract

Primary diagnosis is carried out during the planned ultrasound screening of pregnant women. Already in the second trimester, the lens is visualized on ultrasound as a dark spot (normal). There are cases when the second ultrasound still cannot reliably exclude or confirm the diagnosis, and then this can be done in the third trimester. It is important to understand that at this stage the diagnosis cannot be 100% confirmed, but the disease can be suspected, and statistics show that the method is highly reliable.

After the birth of a child, the pediatrician will be able to notice only an intense clouding of the lens of the central localization. Most often, a cataract cannot be diagnosed by physical examination. An examination by a pediatric ophthalmologist is mandatory for all newborns. The specialist will be able to suspect and confirm the diagnosis of congenital cataract, noticing even a slight violation of the passage of light through the lens. Also, the doctor will detect strabismus and nystagmus. Since congenital cataract accompanies many intrauterine infections, metabolic disorders, chromosomal pathologies, when diagnosing these diseases, the child will be examined to exclude eye defects.

For the diagnosis of congenital cataract, the following instrumental methods are used: ophthalmoscopy , slit biomicroscopy , ultrasound of the eyeball . All of them make it possible to verify the change in the transparency of the lens and to exclude similar diseases in the clinic. In particular, retinopathy in children is also characterized by blurred vision and strabismus, but in this case, the cause is damage to the retina, and examination with an ophthalmoscope will determine this. Tumors of the outer part of the eye can significantly reduce vision, as can congenital cataracts. Visual inspection, ophthalmoscopy, ultrasound methods and X-ray diagnostics help to differentiate them.

Treatment of congenital cataract

Conservative methods of treatment are justified only with a slight clouding of the lens. In therapy, cytoprotectors and vitamins are used. However, most often, congenital cataracts are treated surgically. Surgical removal should be done as early as possible to allow for proper eye development. Cataract surgery – lensvitrectomy – is considered the least traumatic in childhood, therefore it is performed most often. The condition after removal of the lens is called aphakia and requires long-term dynamic observation and vision correction.

Aphakia is corrected with glasses or contact or intraocular lenses. Observation by an ophthalmologist is necessary in order to exclude possible postoperative complications, in particular, glaucoma . A few decades ago, the list of complications was more extensive, but with the introduction of lensvitrectomy, most of them were reduced to a minimum. So, cases of retinal detachment , corneal edema, endophthalmitis and amblyopia are extremely rare .

Prediction and prevention of congenital cataract

Modern methods of surgical treatment provide a favorable prognosis in most cases. Removal of the affected lens at the age of up to six months (better in the first weeks and months) and further vision correction contribute to a good social adaptation of children in adulthood. It should be noted that monocular congenital cataracts respond to treatment much worse and currently give the greatest number of complications associated with this disease. In addition, cataract is extremely rare in isolation, so the prognosis is also determined by concomitant diseases: infections, metabolic disorders, chromosomal pathologies, etc.

Prevention of congenital cataracts is carried out during pregnancy. It is necessary to exclude the contact of a woman with infectious patients, to minimize the impact of teratogenic factors (alcohol, smoking, radiation methods of diagnosis and therapy, etc.). Women with diabetes should be monitored by an endocrinologist throughout pregnancy. Chromosomal pathologies in most cases are diagnosed before childbirth, and then a woman can already decide to terminate a pregnancy or deliberately carry a child. There is no specific prophylaxis for congenital cataracts.

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