Keratoconus is an often congenital and familial disorder of the cornea, which is usually caused by two-eyed (for example in allergies, inflammation and accidents), often by previous laser treatments of the cornea (Lasik for example).
The cornea receives an increasing protrusion (conus) and thus central thinning, which despite glasses or contact lenses continuously leads to a reduction in visual acuity, as the cornea determines the refractive power of the eye to a considerable extent. Those affected often notice increased glare sensitivity and halos (rings of light around the light source). In addition, visual aids (glasses / contact lenses) have to be readjusted at ever shorter intervals due to an increasing astigmatism of the cornea.
At the onset of the disease, the keratoconus usually produces no symptoms and is indistinguishable from a normal corneal curvature corrected by a spectacle lens for the patient. Therefore, these diseases of the cornea are usually discovered at random on the occasion of an ophthalmological inspection. It must be monitored by a doctor and regularly examined using a topography. Progressive Form: This is aggressive and can be felt at an early age. With the progression of the disease, the correction of visual acuity by means of spectacle lenses and contact lenses becomes more and more difficult, because the bulging of the cornea is irregular.
If the protrusion of the cornea increases further, then the time comes when visual aids can no longer be worn because they do not improve vision. In addition, the cornea threatens to break through the permanent thinning in the central area. The cone, the thinnest point with the largest protrusion, shifts within the cornea. This spot can break through and scar. This irreversibly reduces the visual acuity.
The only treatment option so far was to remove the diseased cornea and replace it with a donor cornea (corneal transplantation / keratoplasty). However, such an operation is an organ transplantation with the associated risks and complications, and adequate vision is often not achieved.
Corneal Crosslinking – What Is It?
Crosslinking is a method of mechanical stabilization of tissues.
How does Crosslinking work?
Crosslinking causes an increased number of cross-links between the fibers of a fabric. This is similar to a net that receives additional bracing and thus becomes more mechanically stable.
Crosslinking of the cornea
Crosslinking of the cornea is achieved by a combination of UV irradiation with administration of riboflavin eye drops (vitamin B2). The intensity of the UV radiation is chosen so that the underlying under the cornea eye structures are not affected. Both the eye lens, as well as the retina thus takes no harm in the Crosslinking therapy.
The therapy can be performed on an outpatient basis, takes approximately 2 hours with preparation and is done under local anesthesia. In a first step, the uppermost layer of the cornea, the epithelium, is removed in advanced findings. This is necessary so that the riboflavin eye drops (vitamin B2) can enter the cornea. At a less advanced stage, the epithelium may be unaffected (transepithelial crosslinking). Subsequently, the cornea is treated with UV-A light. Finally, the eye gets antibiotic eye drops and tear substitutes for better wound healing.
Goal of therapy
The aim of the therapy is to stabilize the protrusion and thinning of the cornea. The disease can not be reversed, but at best „frozen“. In individual cases, further cross-linking may become necessary for stabilization.
After the operation
In the first 24 to 48 hours, epithelial pain is normal, but it has disappeared completely afterwards. For relief, every patient gets eye drops and tear substitutes. The vision may be temporarily slightly limited, but increases significantly after a short time after the therapy. Often one also achieves an increase in the visual performance, which, however, is individually different and not guaranteed.
Basically, a long-term supply with an intraocular contact lens (VisianICL) is the best possible correction option. The vision is better than with glasses or conventional contact lens.