Congenital Diseases of the Lens

Congenital dislocations of the lens.

Etiology. Hereditary defect of metabolism of the connective tissue.

It is often combined with other congenital defects of cardiovas­cular, musculoskeletal system.

The Marfan's syndrom is characterised by subluxation of the lens, high growth, arachnodactily, fragility, weakness of the liga­mentous apparatus.

The Marchesani's syndrom is characterised by subluxation of the lens, microphakia, myopia, ditachment of retina, low growth, short trunk, neck, extremities, limitation of joints movement.

Lenticonus (anterior and posterior) is a change of the form of the lens surface in which posterior or anterior pole of the lens as­sumes a conical shape.

Microphakia is a reduction of the sizes of the lens with spheriJ cal shape. It is combined with myopia. It can block the pupil ape« ture, that causes development of the phakotopic secondary glau­coma.

Coloboma of the lens is a defect of equatorial edge of the lens. I In large coloboma astigmatism and myopia usually occur.

Congenital cataract may be following. Hereditary in the Dawn'si disease caused by trisomia of chromosome 21 and antenatal, be8 cause of illness of the mother during pregnancy (influenza, rubel<8 la, toxoplasmosis) or consequence of influence of the various adfl verse factors of external and internal environment (intoxication J ionizing radiation, avitaminosis).

The cataracts may be unilateral and bilateral.

Due to visual deprivation in congenital cataract complications de-| velop quickly: amblyopia, strabismus, nystagm. Frequently cataract! is combined with the anomalies of refraction, microcornea, microph-J thalmus, congenital diseases of the retina, choroidia, and optic nerveS

Depending on presence or absence of these complications and-accompanying pathology congenital cataracts are divided into:

1. Simple cataract.

2. Complicated congenital cataract.

3. Congenital cataract with associated diseases.

In dependence on localization and form of opacity, congenital cataract may be:

— zonular or lamellar — grey opacity in separate layers of the lens as circle with radial projections resembling the spokes in the wheel, popularly known a "riders";

— complete (diffused);

— polar — anterior and posterior;

— coronary;

— punctate;

— starshaped;

— axial;

— pyramidal;

— spinde;

— atypical (polymorphic);

— membranous;

— semiresolved.

Congenital cataracts of any type may be of three degrees: 1. The visual acuity is 0.3 and more (diameter of opacity is up

to 1.5 mm).

2. The visual acuity is 0.2-0.05 (diameter of opacity is 2-3 mm).

3. The visual acuity is less than 0.05 (diameter of opacity more _than 3 mm).

Treatment of congenital cataracts is only operative — removal ₀f the lens. At the third degree of congenital cataract it should be operated early. Cataracts of the first and second degree are oper­ated at the age of 3-4 years. Before this time the pupil is widened, pleoptic treatment is carried out.

Kinds of operative treatment: aspiration-irrigation, phakoemul-sification, laser phacopuncture (laser discision in the membranous cataracts).

Operation and postoperative period have easier current, than in the adult, but the results are worse, because there are compli­cations and associated pathology, which usually are absent in adults.

Date: 2014-12-21; view: 1000