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Keratoconus
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Keratoconus

Keratoconus is a degenerative disease of the eye, the effect of which is a loss of the cornea’s spherical shape which then takes the shape of a cone. This is known as corneal ecstasia.

Keratoconus has the effect of decreasing visual acuity because it is accompanied by a major irregular myopic astigmatism to which in some cases a central opacity of the cornea is added. Keratoconus does not necessarily make a person blind, but sight diminishes more and more due to the deformation of the cornea and irregular astigmatism.

Keratoconus generally affects both eyes, but develops differently in both eyes.

What are the symptoms?

Keratoconus is often diagnosed in an adolescent or young adult, between ten and twenty years old, who seeks medical help due to blurred vision and/or visual distortion. These problems may be accompanied by hypersensitivity to light (photophobia) and reflection problems.

Who is affected?

It is a rare disease which generally appears in adolescence and would affect about 50 to 230 people out of 100,000. Female preponderance is not certain.

The disease is spread uniformly throughout the world. Apparently, there is not geographic, cultural or social disparity.

What are the causes?

The true causes of keratoconus currently remain unknown. Researchers have, however, identified several factors which appear to favour it. The first of these is heredity.

The role of heredity has been suggested by observing numerous family cases. In particular, it has been able to be established that 7% of patients suffering from keratoconus had at least one other member of their family affected by keratoconus. Nevertheless, the risk of being affected due to descendent is assessed at less than 10% when one of the two parents is a keratoconus carrier.

Keratoconus may accompany other anomalies such as Down’s Syndrome, certain diseases affecting the conjunctive tissue (Ehlers-Danlos syndrome). They also occur in individuals with a predisposition to pathologies like asthma or eczema, or in people who have a tendency to rub their eyes.

What is the evolution?

Keratoconus is progressive: it takes years to fully develop and can stop at any stage. It has however been noted that overall, the disease progressed especially between the age of 10 and 20 years. Between 20 and 30 years old, progression becomes slower and very reduced after 30 years of age.

In a more advanced stage, keratoconus leads to a rapid decrease in visual acuity due to the deformation of the cornea. Sometimes the central cornea develops a scar that also contributes to a loss of eyesight.

Sometimes, a patient complains of “pulsatile” vision especially after physical exercise. This shows the existence of an already considerable thinning of the cornea.

The ultimate stage of acute keratoconus rarely appears. The cornea then thins to such a point that this may cause a rupture of the endothelium with appearance of an oedema.

How is it diagnosed?

Clinical examination will attempt to show up the disease’s characteristic alterations.

Deformation of the cornea and irregular corneal astigmatism can be diagnosed by various methods:

Examination with a slit lamp enables eccentric protrusion of the cornea to be located. In a more ad-vanced stage, the cornea becomes thinner and corneal opacities appear.
Keratometry enables the curvatures of the cornea to be measured and is therefore of major im-portance. In effect, in the initial stage, irregular astigmatism is the only element and it is naturally es-sential to be certain that it did not exist beforehand.
Corneal topography is an examination that enables the cornea to be mapped and therefore makes an image of irregular astigmatism as if the contours of a mountain were being studied. This examination gives graphic results which tell you a lot and which can be compared from one examination to the next Unfortunately, not all ophthalmologic practices have a topographer.

How can it be prevented?

Keratoconus cannot be prevented, but its worsening can be prevented by avoiding rubbing one’s eyes. This practice must be avoided at all costs.

how to treat it?

    Introduction

    Ultra-violet crosslinking

    Visual rehabilitation after UV-CXL (or crosslinking by UV rays and visual rehabilitation in patients suffering from keratoconus)

    Transfixiant keratoplasty or corneal transplant

    DSAEK (Descemet Stripping Automated Endothelial Keratoplasty)

    Deep anterior lamellar keratoplasty (DALK)

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