Example of vision with keratoconus
Keratoconus is a disorder that causes a deformation of the cornea: its surface does not keep a normal spherical shape, but tends to loosen (generally in the central or in the lower part).
Keratoconus worsens with time and from the clinical point of view is classified by three stages:
- Stage I: it is the initial stage. During this phase keratoconus can be confused with an ordinary astigmatism which, generally, does not change throughout the life of a person.
- Stage II: an irregular astigmatism appears, that can be corrected just partially, with the use of eyeglasses.
- Stage III: the corneal deformation is very pronounced and the part of the cornea that tends to loosen begins to get thinner. The cornea often becomes less transparent causing sight to be really compromised. In this case the use of eyeglasses does not provide the patient with a satisfactory degree of visual acuity.
Parasurgical treatment with cross-linking
Cross-linking is a technique that involves a combined application of riboflavin (B2 vitamin) in solution with dextran (a sugar) at 20% in a yellowish gel-like composition and which is put in contact with the cornea.
The application of this solution (Ricrolin®) to the corneal tissue and the following illumination with UV-A light (370nm), activates oxygen free radicals that produce a change in the collagen structure and the development of new molecular organisation.
We can observe this effect in the increase of the thickness of the collagen fibres with a consequent stiffness of the cornea and the increased resistance to the physiological intraocular pressure.
The result of the cross-linking treatment is the interruption of the corneal structural collapse and thinning, but it does not eliminate the dependence on glasses or contact lenses.
The problem can be faced in two different ways. The first one employs the femtosecond laser and the post-operative course is completely painless. In the second one, where the corneal epithelium is removed, the surgery is painless, while in the following 2-3 days your eye may feel a bit uncomfortable and sensitive to light, because of the recovery period of the corneal epithelium.