Keratoconus

Keratoconus, or conical cornea, is a genetically determined pathology of the cornea, the external manifestation of which is a change in its shape. The cornea becomes thinner in the center, stretched out in the form of a cone.

[1], [2], [3], [4], [5], [6]

Causes of the keratoconus

The keratoconus develops due to the underdevelopment of the mesenchymal tissue of the cornea and sclera. The entire outer capsule of the eye loses its usual elasticity.

[7], [8], [9]

Symptoms of the keratoconus

The keratoconus disease begins at the age of 10-18 years, and sometimes even earlier. There is an incorrect astigmatism, which can not be corrected. The patient often changes glasses due to the fact that the degree and axis of astigmatism change. The change in the axis of astigmatism can sometimes be noted even with a change in the position of the head.

The process is more often bilateral, but it does not always develop equally and simultaneously in both eyes. Observation of identical twins with keratoconus showed that they had the same symptoms at the same age and recorded the same refractive data of the eye, cornea, and the degree and axis of astigmatism. A few years later, both twins in the pair eyes also formed a keratoconus simultaneously.

The weakness of the elastic framework of the cornea is noted mainly in the central section. The apex of the conical cornea is always lowered downwards and does not correspond to the projection of the pupil. This is associated with the appearance of an incorrect astigmatism. When carefully examined in the light of the slit lamp, one can see hardly noticeable thin strips almost parallel to one another, localized in the central part of the Descemet shell - the cracks of the elastic membrane. The appearance of this symptom can be considered the first reliable sign of keratoconus. The thickness of the cornea in the center gradually decreases, the depth of the anterior chamber increases, the optical power reaches 56-62 D. In the keratotopography study, the characteristic symptoms of changes in the optical properties of the cornea are revealed: displacement of the optical center downwards, the presence of abnormal astigmatism, large differences in the strength of refraction between the opposite sections of the cornea.

When large cracks appear in Descemet's shell, the state of the so-called acute keratoconus suddenly appears. The stroma of the cornea is impregnated with the intraocular fluid, cloudy, only the most peripheral parts remain transparent. In the acute stage of keratoconus, the central part of the cornea is significantly thickened, sometimes with biomicroscopy one can see crevices and cavities filled with liquid. Visual acuity is sharply reduced. Edema in the center of the cornea gradually resolves, sometimes even without treatment. This process is always completed by the formation of a more or less gross scar in the central part and thinning of the cornea.

[10], [11]

Treatment of the keratoconus

In the initial stages of keratoconus, contact vision correction is very effective. However, with progressive thinning and protrusion of the cornea, the contact lens is not retained at the apex of the cone.

A radical method of treatment of keratoconus is a through subtotal keratoplasty with excision of the entire altered cornea. In most patients (up to 95-98%) after surgery, a high visual acuity is observed - from 0.6 to 1.0. A high percentage of transparent corneal transplant engraftment is due to a number of factors. With keratoconus in the cornea there is no inflammation, no vessels, as a rule, there is no other pathology of the eye.

The indication for the operation is determined not by the degree of stretching of the cornea, but by the state of the eye function.