Until 2000, there were no treatments to stop so-called ectatic corneal diseases (keratoconus, PMD, keratectasia). As a result, there was nothing left but to wait until the cornea bulges so strongly that it was no longer possible to correct vision with glasses or contact lenses. At this stage, only a complex and high-risk corneal transplant could improve vision again.
Thanks to the invention of cross-linking by Prof. Dr. Dr. Theo Seiler, among others, there is a minimally invasive method to effectively stop the progression of these corneal diseases.
At Eye Zurich, we have extensive experience from many years of close cooperation with the inventor of corneal cross-linking.
The cornea of the eye consists of a framework of collagen fibers that are specially oriented. This arrangement creates a high level of stability and transparency, which is important for eyesight.
In patients with ectasia, this stability is reduced, causing the cornea to bulge ever further forward.
Through cross-linking, the collagen fibers are “cross-linked” and thus solidified. The primary goal of treatment is to stabilize the current shape of the cornea, i.e. to “freeze” it and prevent the progression of the disease.
The treatment takes place in four steps.
Cross-linking binds the collagen fibers together, which on the one hand increases stability and on the other hand also causes partial flattening.
The treatment itself is virtually painless and is performed under local anesthesia with anesthetic eye drops. After cross-linking, moderate to severe pain occurs, which subsides after two to three days. At first, vision is significantly reduced and sensitivity to glare is noticeable.
Returning to everyday activities and work is usually possible after 7-14 days.
In the last two decades, cross-linking treatment has been continuously developed. The output and duration of irradiation or the pattern of irradiation were optimized.
The irradiation time lasts 30 minutes with an energy of 3 mW/cm2
The irradiation time is reduced to 10 minutes during which the energy is reduced to 9 mW/cm2 is increased. The treatment time is significantly reduced without reducing the cross-linking effect.
The radiation pattern is individually adapted to the patient's cornea or keratoconus. As a result, the healing time is reduced and the keratoconus regresses easily.
In less advanced forms of keratoconus, the cornea can be regularized first before cross-linking with a laser (PRK). This regularization makes the cornea rounder again, which can later improve visual acuity without glasses or contact lenses.
Since the cornea flattens out slightly up to two years later due to the cross-linking effect, it makes sense to carry out laser correction later to improve visual acuity.
The top layer of the cornea is not removed during these procedures, which results in faster healing. However, numerous studies have shown that the effect of this method is not enough, so we do not recommend using these protocols.
With all types of cross-linking, the cornea is stiffened and flattened to varying degrees. In approximately 95% of treatments, the progression of keratoconus is stopped and partially regressed as a result.
Immediately after treatment, a bandage contact lens is placed on the cornea. As a result, the epithelium (top layer of cornea), which is removed for treatment, can heal more quickly. To prevent the blink of the eye from slowing down the healing process, the eye is closed with an additional bandage.
The cornea is the tissue with the highest density of sensitive nerve fibers in humans. As a result, the body reacts to the treatment with increased lacrimation, severe burning and shooting pain.
Extensive pain management helps to make the first few days after treatment more pleasant.
The contact lens is carefully removed and it is checked whether the top layer of the cornea (epithelium) that was removed for treatment has healed. As soon as this is closed, eye drops (FML) containing cortisone are used to control the inflammatory response. The anti-inflammatory eye drops (FML) are slowly removed over four weeks. In addition, we recommend using moisturizing eye drops (Optava) regularly.
Vision recovers slowly, which can take up to several weeks.
With so-called OCT imaging (optical coherence tomography), it is possible to show what percentage of the cornea was successfully treated.
In the one-month check, the current topography is compared with the images before the operation. If the cornea is completely cleared, eye drops containing cortisone can be stopped.
Since the shape of the cornea is usually not completely regular even after cross-linking treatment, eyesight can only be improved to a limited extent with glasses. Shape-stable, i.e. hard, contact lenses cover the unevenness of the cornea and thus create a beautiful, spherical surface. This allows a sharp image to be created on the retina despite corneal deformation caused by keratoconus.
Further investigations are needed to rule out possible long-term effects such as scarring and inflammation in the area of the cornea.
In order to be sure that keratoconus has actually been stopped, further checks with topography measurements will be carried out in the first few years after treatment. Since the cornea can still slightly deform up to two years after cross-linking, it is possible that glasses or contact lenses may have to be adjusted more often during this time.
Since keratoconus is an inherited disease, it makes sense to examine the siblings and children of a person affected. The earlier cross-linking is performed, the better the prognosis for vision after the procedure.
In keratoconus, the cornea becomes thinner and bulges forward, making vision increasingly poor.
UV-A is the weakest type of UV radiation in natural sunlight and has the property that it cannot penetrate too deep into human tissue.
Yes, those cross-linking techniques that do not remove the epithelium ((epi-on protocols) are significantly less effective, according to scientific publications.
Yes, using anesthetizing eye plugs to anesthetize the cornea. This makes the treatment almost painless.
The entire treatment takes approximately 45-60 minutes.
Since healing takes several days and is not the same for all patients, we usually first operate on the eye where the ectasia has progressed further. First, when the first eye has completely recovered, we treat the second eye.
Depending on the protocol used, the costs for cross-linking treatment vary between 1450.- and 3000.- CHF.
Cross-linking treatment was recently added to the health insurance provider's list of benefits.
Yes, these lenses are listed on the MiGeL (list of products and objects), although the remuneration is usually not quite sufficient to cover the costs of the specialist optician.
The biggest risk is a corneal infection in the first few days after cross-linking. However, this risk is minimized by administration of antibiotics after the procedure and is less than 0.1% for our patients.
Radiation rarely causes corneal opacities; these can be treated with eye drops containing cortisone.
As long as ectasia continues to progress, your cornea will continue to thin, your vision will continue to deteriorate, and it is likely that you will need a corneal transplant at some point.
If keratoconus persists in childhood or adolescence, the risk of rapid worsening is particularly high and treatment should therefore be carried out as soon as possible. For young children, anesthesia by an anesthetist is necessary. In this case, pain treatment after the procedure must be adjusted to the age and weight of the child.
