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keratoconus

Index

Il cheratoconus is a non-inflammatory degenerative disease affecting the cornea.

The cornea is the transparent tissue that covers the front of the eye and is the most important lens in the visual system. Its transparency allows the passage of light inside the eye and its dioptric power contributes to the focus of the images on the retina.

In patients with keratoconus the corneal tissue tends to thin and wear out in the central part. In this way, the cornea loses its normal spherical symmetry over time and takes on a cone shape (hence the name of the pathology).

Keratoconus is a relatively rare disease, has a multifactorial origin but has an important hereditary component, it affects the male gender more than the female one. It usually occurs during puberty and affects both eyes.

Eye with keratoconus

Pathology progresses through several

Symptoms

The onset of keratoconus is manifested by the appearance of pronounced refractive defects, in particular theastigmatism but very often also myopia (refractive myopia). In the early days, the visual defect can be corrected with eyeglasses, but later the curvature of the cornea becomes very irregular and it is necessary to use specific contact lenses for keratoconus, which have a high tolerability.

As the disease progresses to the advanced stage, various complications can arise. The first is that contact lenses no longer adhere to the cornea and can no longer be worn, consequently the refractive defect cannot be corrected optimally. In addition, when the corneal tissue thins beyond a certain limit, scarring appears that opacifies the cornea. Opacification significantly interferes with the passage of light, helping to increase refractive defects and often causing a very annoying sense of glare.

People with keratoconus have a distortion of images of an extent directly proportional to the progress of the disease and, since it is difficult to obtain clear vision with corrective lenses, patients with keratoconus often have visual difficulties both from far and near.

In the advanced stage there is a risk of rupture of Descemet's membrane and training of corneal hydrops (acute keratoconus).

Diagnosis

Keratoconus can be diagnosed and monitored thanks to instrumental tests such asophthalmometry, which measures corneal parameters, the pachymetry, which determines the thickness of the cornea, and the corneal topography, which allows to map the curvature of the cornea. In recent years, new survey techniques have been introduced, such aslaser interferometry , Scheimpflug room, which allow to perform a corneal topography with progressive analysis of all corneal layers. These tests are particularly important to follow the evolution of keratoconus and to be able to prescribe customized contact lenses able to correct the refractive defect in an optimal way.

Until some time ago it was thought that the use of contact lenses could help prevent or slow down the exhaustion of the cornea affected by keratoconus, but today it is known that, on the contrary, contact lenses with a curvature less than that of the cornea they can cause abrasions or ulcerations in the central part of the cornea itself, giving rise to severe opacification processes. For this reason, corneal topography is an essential examination to be able to prescribe contact lenses to a patient with keratoconus and this examination must be repeated at least every 6 months since, by its nature, the pathology progresses rather quickly and the curvature of the cornea undergoes. important changes even in a relatively short time.

Treatment

In most patients the progression of keratoconus stops spontaneously around the age of 30-40, but in a small percentage of cases the disease progresses to the point of causing severe damage to the corneal tissue and visual impairments that require the cornea transplant (keratoplasty).

Today there are therapeutic procedures aimed at slowing down and containing the deformation of the cornea affected by keratoconus, in order to avoid the onset of serious damage and the need to have to resort to transplantation. Some, such as corneal cross-linking, are already in use but effective only if performed in the initial or intermediate stage of the disease; other therapeutic options, for example based on gene therapy, are being validated.

Cornea transplantation consists in the removal of the deformed cornea and its replacement with a healthy cornea from a donor. In reality, nowadays it is more correct to speak of "graftInstead of transplantation, since the portion of tissue that is removed and grafted is rather limited. This type of surgery has a high success rate with very rare rejection events and good visual recovery.

Giant retinal detachmentPostoperative retinal detachment cerclage

Pathology and treatment on video

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