Keratoconus

 

The conical cornea characteristic of keratoconus.

Keratoconus is a disease of the cornea (corneal dystrophy, progressive non-inflammatory) that usually affects both eyes (85% of cases). The problem arises when the central part of the cornea begins to thin and to curve progressively outwards. Occurs then an irregular curvature of the cornea, which loses its spherical shape, becoming conical. Has a higher frequency in females and appears in relation to dysfunction of the endocrine glands (pituitary, thyroid). There may also be a hereditary predisposition. The disease can occur already during adolescence.

Symptoms

The irregular curvature created changes the refractive power of the cornea, resulting in distortion of the picture, and a blurred vision both near and far. The patient complains, however, a loss of vision, especially from afar. The quality of vision continues to deteriorate irreversibly; the risk is to be exchanged with a myopia associated with astigmatism.
After a few years the symptoms appear in the presence of keratoconus: the eye becomes brighter, the objects that are reflected on the cornea appear crooked. The eye, when viewed in profile, shows a characteristic protrusion of the ocular surface transparent.
Using the biomicroscope, there was a significant decrease in thickness on top of the cornea. Over time it becomes opaque due to an alteration in the contribution nutrition.
If the disease is left untreated, the ulcer summit; appear pain, tearing and spasm of the eyelids. These changes in the cornea in fact produce an alteration in the arrangement of corneal proteins, causing microcicatrici that further distort the images, and - in some cases - prevent the passage of light, giving a sense of annoying glare, especially at dawn and dusk. Another tool for the diagnosis of this pathology is the topography of the eye: allows a 'mapping' which highlights the deformation of the cornea (which acts as a "lens" external, unlike the lens that is located within the eyeball ). This examination can be done at many public or private laboratories. Keratoconus is classified as a rare disease and therefore exempted from co-payment for medical treatment and examinations.

Therapy

In mild forms using rigid contact lenses to correct the vision defect. The most severe forms, which are progressive and which lead to a bulging and thinning of the cornea, require surgery such as transplantation of the cornea (keratoplasty).
Since 2002 he has been introduced lamellar keratoplasty. In practice, it is replaced the entire cornea, but only the thickness of the outer, the one affected by the disease.
A relatively new surgical treatment is represented by intracorneal inserts. The technique, which significantly improves the visual acuity of patients, the plant consists of microscopic synthetic inserts just below the transparent surface of the eye, at the periphery of the cornea. The result is that if it follows a cornea flatter and sharper vision.

The new frontier: the corneal cross-linking

In 1997 he invented at the University of Dresden in Germany the corneal cross-linking. Since then it is used in almost every country in the world.
In 2005, the General Hospital of Siena in Italy has begun an investigation into the effects that such a technique has on the corneal collagen. To accomplish this research has used a tool known as a confocal microscope.
The technique, which was launched in Germany in 1997 but released only in recent years, consists of instilling a few drops of vitamin B2 (riboflavin) on the cornea and, at the same time, exposing the cornea to ultraviolet light. The chemical reaction of UV-A rays that stimulate riboflavin leads to a strengthening of the links in corneal collagen resulting in a hardening of the cornea. Early studies have shown that it is possible to block the evolution of the disease and, in many cases, there is a decrease of the curvature of the cornea (2 diopters on average).

The technique is risk-free if it is designed to comply with the protocol, and widely experienced in Dresden.

Some ophthalmologists Italians have begun to make changes to this protocol but the effectiveness of these changes has been strongly questioned in the course of the conference held in Dresden in December 2008, on the occasion of the tenth anniversary of the application of cross-linking.
The use of eye drops different from the original and the use of machines different from the one developed in Dresden could lead to reduced efficacy of the treatment itself.
In 2006 he started a multicenter study that involved, as well as the University of Siena, many other eye care centers Italians.
From 1 January 2007, this therapy has been recognized at both the national (Italian) and supranational (EU) as an official cure. In 2007, thanks to the exceptional internationally recognized, have multiplied the centers who practice cross-linking. However, not everywhere is carried out in a regime of complete selflessness, but only in certain regions where it is reimbursed by the Regional Health Service. In Tuscany, the cost of treatment is entirely supported by the Regional Health System (you only pay the ticket).


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