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Collagen Cross-Linking using Riboflavin and UVA exposure

Collagen Cross-Linking is used to stabilize a weakened cornea due to a keratoconus or keratectasia.

A keratoconus is a hereditary corneal disease typically diagnosed during adolescence or early adulthood. It occurs when the normally round dome-shaped cornea progressively thins, causing a cone-like bulge of the cornea to develop. The keratoconus progresses at variable speed and causes a progressing reduced visual acuity that can make simple daily tasks, such as driving, watching television or reading difficult to perform. The incidence of keratokonus in Europe is about 1 : 2000.

So far, treatment methods such as rigid contact lens or intracorneal ring segments aimed only at the correction of the refractive error without any effect on the progression of the disease. It is estimated that eventually about 20% of keratoconus patients require surgical intervention (corneal transplant) to restore corneal anatomy and eyesight.

The actual cause of keratoconus is not yet known, but there have been studies to suggest a genetic and inherited link to the disease.

Corneal ectasia
(also called "kerectasia") is a rare but serious complication of LASIK surgery. If the laser removes too much tissue during LASIK or the flap is cut too deep, the structure of the cornea can be weakened. This weakening can cause the cornea to bulge forward causing an increasing astigmatism and distorted vision.

Why collagen cross-linking?
Collagen cross-linking is a relatively new treatment approach based on photo-chemical reactions within the corneal tissue. It uses a photosensitizing agent, riboflavin (vitamin B2), and ultraviolet light (UVA) exposure which leads to an increased formation of bonds between collagen molecules ("collagen cross-linking").

What happens during the procedure?

The treatment is performed under topical anesthesia. First, the outer cell layer of the cornea (epithelium) is removed. In 5 minutes intervalls, riboflavin (vitamin B2) eye drops are applied on the cornea to increase UVA absorption. The eye is then exposed to UVA light for about 30 minutes during which the patient fixates on a bright lamp above his head. The procedure is painfree. After the treatment, eye drops are applied and a soft contact lens is worn until the surface of the eye has healed. Follow-up exams at the eye doctor are necessary to ensure proper healing.


Collagen cross-linking has been used since 1998 to treat thousands of keratoconus patients. Allthough collagen cross-linking increases corneal rigidity or stiffnessis, it is not a cure but aims to halt the progression of the condition.
Please note that it may take up to 6 months for the treatment to show effect.

What are the possible complications and side effects of cross-linking?
During the first days after the procedure patients may experience pain and a foreign body or burning sensations. An increased sensitivity to light and blurred vision may be noticed for up to a few weeks. Severe complications such as infections have not been described after this procedure.

Treatment costs
In Germany, the treatment costs for the collagen cross-linking procedure are not covered by public or private health insurances. This fact also applies in cases of documented intolerance to eyeglasses or contact lenses. Currently, the costs for the preoperative and postoperative exams are also to be paid by the patient and are calculated in accordance with the German coding system for the calculation of medical services (Gebührenordnung für Ärzte – GOÄ).
Please feel free to inquire about the costs for this procedure.