What is megalocornea?

Megalocornea is a rare genetic pathology of the visual apparatus, in which the diameter of the cornea increases by 2 or more millimeters from the normal values. For example, a diagnosis can be made if the newborn has a diameter of 11 mm, which is higher than normal. The clinical picture of the disease is very individual: the anomaly may not have severe symptoms, but in rare cases, numerous ophthalmic disorders develop.

Features of the disease

Until the beginning of the 20th century, megalocornea was considered an abortifiable version of glaucoma.The idea of ​​the disease was radically changed by the German researcher B. Kaiser, revealing the genetic nature of the disease.In 90% of cases, the pathology is transmitted along the X-linked chromosome, so megalocornea is diagnosed more often in boys.In all other cases, inheritance is autosomal recessive, that is, a person can be a carrier of a gene, but not suffer from a disease.

The disease is congenital, so the first signs are found in the maternity ward.In most cases, the normal transparency of the cornea does not occur, despite the fact that the anterior chamber can be enlarged compared to the norm. In addition, the eyeball and ophthalmic tone also do not suffer.The primary task of physicians in the detection of typical signs of the disease is to differentiate the ailment from congenital glaucoma (hydrophthalmic).There are several distinctive differences between megalocornea and other similar diseases:

• There are no strong thinning or deformation of the limb;
• There are no defects in Descemet's shell;
• Functional disorders typical of glaucoma do not occur;
• Intraocular pressure is always normal;
• The disease does not progress, except for the increase in the diameter of the cornea is proportional to age.

Megalocornea is diagnosed at a primary examination of a newborn, so it is possible to monitor the course of the disease from the first days of a child's life.

Causes

The disease has an exclusively genetic etiology and can be transmitted both from the carrier of the defective gene, and directly from the mother to the child.Megalocornea occurs during the formation of the visual apparatus in the early stages of pregnancy. Normally, the "eye glass" should change to a spherical shape by the 6th week, but with this pathology such changes can occur later. As a result, the diameter of the ciliary belt and adjacent structures increases in size.Structural elements of the cornea are anatomically distributed normally, but there is an increase in its diameter and subsequent thinning usually in the central parts.

Main symptoms

In most clinical cases, the disease is completely asymptomatic and rarely progresses. The main sign of megalocornea is an enlarged cornea, and the transparency of its membrane remains.The clinical picture largely depends on the severity of the violations of the structural components of the cornea, and in their absence, the visual function remains normal. In severe megalocornea the following symptoms can be expressed:

• When bilateral lesions occur dystrophic disorders, and also it is possible to notice dispersion of a pigment on all surface of a cover;
• A slight visual impairment may develop, and also periodically there can be various ophthalmological distortions of perception of objects. Myopia and astigmatism are formed;
• In rare cases, there is a stretching of the lens muscle apparatus, which can lead to a shivering of the iris when the eyeball moves sharply;
• There is a chance of developing secondary glaucoma.This is complicated by increased intraocular pressure, a violation of the outflow of fluid in the vitreous.

If there is a large increase in the size of the diameter of the cornea, when viewed visually it looks slightly convex, then in the future it can affect the visual acuity.

Possible complications

All the complications in megalocornea are related to how much the cornea was deformed during embryonic development.Thus, as the depth of the anterior chamber increases, ametropia may develop, and with the development of a bilateral disease, the risk of anisometropia increases.The most terrible consequence of the violation of the diameter of the cornea is congenital strabismus, which can only be corrected in an operative way, as well as the development of unilateral or bilateral amblyopia.

Congenital strabismus in children

In rare cases, megalocornea is complicated by various dysfunctions of the pupil, for example, there is an ectopia or embryotoxone.

Treatment

Ophthalmologists do not recommend the treatment of this disease, if there are no complications, and visual functions are normal.This is because surgical or conservative treatment of pathology can lead to the progression of the disease or the occurrence of complications after surgery.

When ophthalmic disorders are always prescribed the use of corrective contact lenses or glasses, restoration of vision by the laser method is not recommended in connection with the risk of lens subluxation or rupture of the posterior capsules.

If a cataract develops against the background of the disease, then in some cases, its phacoemulsification is appointed with further implant placement in the form of an intraocular lens. This is a complex operation with a high risk of complications, therefore it is performed only by experienced eye surgeons in progressive clinics.The procedure is always performed under retrobulbar anesthesia, and all surgical operations are performed through the corneoscleral incision.

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Prevention

There are no effective ways to prevent the development of this serious pathology.In the presence of illness in one of the parents, during pregnancy, it is necessary to strictly observe all the prescriptions of the doctor, regularly undergo ultrasound and take care of your own health.If nevertheless there was a genetic mutation and the disease appeared, first of all it is necessary to differentiate it from other pathologies, since megalocornea is extremely rare. The disease does not pose a health risk, but after 30 years the chances of developing a secondary cataract increase, therefore it is recommended to regularly undergo an ophthalmologic examination in time to notice the progress disease.

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conclusions

Megalocornea occurs only in 3-5% of the world's population, therefore every child with this defect is immediately registered with an ophthalmologist and controlled for life. Complexity in the prevention and treatment of this disease is due to the genetic nature of the disease, but even with serious complications of the enlarged cornea, there is a chance of partial cure. The development of medicine does not stand still, and in recent years there have appeared effective surgical methods that allow at least to eliminate possible secondary diseases in this pathology.

Also read about such diseases as scotoma of the eye and heterochromia with coloboma.