What is keratoconus and how is it treated?

Keratoconus is an eye disease that affects the cornea, the first and most important “lens of the eye”. In the natural course of this disease, the cornea is progressively deformed causing visual defects such as myopia or irregular astigmatism that are not correctable with glasses or contact lenses and that lead to a significant decrease in visual acuity, being able to reach in its most advanced stages a very severe deterioration of vision.

It usually appears between the first and second decade of life, the speed and degree at which it evolves in each patient is very variable and its frequency, which, due to the undoubted improvement of diagnostic methods, was formerly thought to be very low and nowadays we can find clinical evidence that speaks of up to 6% of the general population. It can affect only one eye, although it usually affects both eyes asymmetrically, both in its evolution and in the degree of involvement.

Causes of keratoconus

The cause of keratoconus is still unknown, although it is thought that there is a genetic factor. In addition, it is more frequent in people who rub their eyes and with collagen diseases or Down’s Syndrome.

Diagnosis of keratoconus

To monitor and treat the disease, ophthalmologists’ offices use measuring instruments called topographers which, in order to be accurate, must examine both the front and the back of the cornea, where the first signs of keratoconus appear. Other devices are also used to measure corneal biomechanics or the cornea’s ability to withstand external (eyelids, trauma, rubbing, etc.) and internal (intraocular pressure) pressures.

Treatment of keratoconus

Treatment should be comprehensive, adapted to each case, and should act on two fundamental aspects: slowing the progression of the disease in cases where it is shown to be unstable and, in cases where it does not progress, improving the patient’s visual acuity.

In mild cases of keratoconus and without evident progression, good vision can be achieved by correcting it with glasses or special contact lenses. Of the latter, the most recommended for treating keratoconus are scleral-supported rigid contact lenses (ICD) and hybrid lenses (Clearcone).

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In more advanced or progressive cases, it may be necessary to resort to surgical treatment, which can be performed by various techniques:

  • Corneal Cross-Linking: it is recommended whenever progression of the disease is suspected or demonstrated, although it should not be delayed excessively, since in very advanced stages that present a great thinning of the cornea it would not be indicated. It consists of subjecting the cornea to ultraviolet radiation after the application of Riboflavin (Vit B2) in order to strengthen and stabilize its internal structure. It is an effective treatment and stops its progression in a high percentage of treated patients.
  • Intracorneal Rings Implant: to treat irregular astigmatism, rings can be implanted in the thickness of the peripheral cornea, which modify the corneal curvature in a personalized way. Intrastromal rings or segments have been used for this purpose for years with good results, being currently much more effective thanks to the Femtosecond laser, which designs with absolute precision and safety both the depth and the position of the intrastromal tunnel where they will be implanted.
  • Corneal transplantation: should be performed in keratoconus that have reached more advanced stages and there is severe corneal thinning and irregularity, which contraindicates other more conservative techniques. It can be performed by selectively replacing the affected layers and preserving healthy tissue (lamellar transplantation), which reduces the risk of rejection and alters less the normal corneal structure, or by replacing the cornea in its full thickness when the corneal alteration is so severe that it prevents the previous one (penetrating transplantation).