Congenital and child cataracts
Cataract is a partial or complete clouding of the substance or capsules of the lens, which is accompanied by a decrease in visual acuity until its complete loss. The opacity of the lens is the leading cause of blindness in the world.
The term " congenital cataract " implies a clouding of the lens already at the time of the birth of the child. The turbidity of the lens during the first year of life is called child cataract. Some lens opacities remain unnoticed at birth, and they are detected only during the examination, therefore, these terms are often considered to be equivalent. Congenital and child cataracts occur with a frequency of 1 case per 2000 newborns.
Congenital and child cataracts can be bilateral( 85%) or unilateral. As a rule, 1/3 of congenital or child cataracts are combined with other diseases( Down syndrome, Hallerman-Stryff-François syndrome, Low syndrome, Marfan syndrome, Alport syndrome).1/3 of all cases of congenital and child cataracts occur as a hereditary disease, which in most cases is transmitted by an autosomal dominant type of inheritance. In addition, there is a possibility of transmission of the disease by autosomal recessive, linked to the X-chromosome type. In 1/3 of the cases, the cause of cataract formation remains unknown. Metabolic diseases( diabetes mellitus, galactosemia, hypocalcaemia, Westphalian-Wilson-Konovalov's disease, myotonic dystrophy) are usually combined with bilateral cataracts.
Intrauterine infection( rubella, cytomegalovirus infection, chicken pox, herpes, syphilis, toxoplasmosis) can also be the cause of congenital cataracts.
Rubella in a pregnant woman can cause fetal damage, especially when infected during the first three months of pregnancy. Systemic manifestations of congenital rubella include heart disease, deafness and mental retardation. Cataract as a result of congenital rubella syndrome is manifested by white pearl clouding of the eye's core. Sometimes a complete cataract with liquefaction of the upper layers of the lens is formed. Live particles of the virus can be isolated from the lens of the child 3 years after birth. Cataract removal can be complicated by excessive postoperative inflammation caused by the release of the virus. Other eye manifestations of congenital rubella syndrome: pigmentation of the retina, involuntary movements of the eyeballs, reduction of the size of the eye, glaucoma, cloudy opacity of the cornea. Despite the fact that congenital rubella syndrome can cause both cataracts and glaucoma, the simultaneous development of these conditions in one eye is not characteristic. The defeat of the organ of vision for rubella reaches 49-53%.
Cataract manifestations depend on its type. With polar cataract changes in the lens lead to clouding of the capsules of the lens. Anterior polar cataract is usually a small bilateral symmetrical non-progressive turbidity, which does not reduce visual acuity. Anterior polar cataract is sometimes found in combination with other eye anomalies( a decrease in the size of the eyeball, the remnants of the pupillary membrane and the anterior lenticone).The posterior polar cataract usually leads to a greater reduction in visual acuity than the anterior one. In most cases, it is stable and rarely progresses.
Cataracts can be first arising or familial. Family posterior polar cataracts usually affect both eyes and are transmitted by an autosomal dominant type of inheritance. The first appearance of a posterior polar cataract often affects only one organ of vision and can be combined with a lens injury or with such an anomaly of its capsule as a lenticone.
Suture or stellate cataract rarely leads to poor eyesight. Two-sided and symmetrical suture cataracts are often transmitted by an autosomal dominant type of inheritance.
Congenital nuclear cataract usually affects both eyes, the intensity of clouding the lens may be different. The eyeball with congenital nuclear cataract, as a rule, is reduced in size.
Capsular cataract is a limited opacification of the anterior capsule of the lens. Capsular cataracts usually do not adversely affect vision.
Zonular, or layered cataract is the simplest kind of congenital cataract. This is a bilateral symmetrical defeat. Turbidity develops as a result of a short-term toxic effect during embryonic growth of the lens. Layered cataracts can be transmitted by an autosomal dominant type of inheritance.
Laminar cataract - clouding of certain layers or zones of the lens, which is revealed during a special examination.
Complete cataract is the turbidity of the entire lens. Some cataracts can be partial at the birth of the child and progress rapidly until the full clouding of the lens. Complete cataract can be one-sided or bilateral and leads to a significant decrease in vision.
Cataract fistula occurs when the proteins are absorbed from the whole or injured lens. In this case, the front and back capsules of the lens are soldered to each other in a solid white membrane. The opacity and deformation of the lens is in this case the immediate cause of a significant decrease in visual acuity.