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Collagen Crosslinking for Keratoconus (CXL)

Corneal collagen cross-linking (CXL) is a technique that was first used over 20 years ago to treat patients with a disease called keratoconus. In keratoconus, the cornea (the front clear window of the eye) can become weak, thin, and irregularly shaped. Instead of keeping its normal round shape, corneas with keratoconus can bulge forward into the shape of a cone causing poor vision. CXL is now being performed for patients with this condition in many offices and hospitals throughout the world.

What does CXL do?

Normal corneas have cross links between its collagen fibers that keep it strong and able to retain its normal shape. In keratoconus, the cornea is weak with too few cross-links. This weakened structure allows the cornea to bulge outwards making the vision poor. The cross-linking procedure adds cross-links or “cross beams” to the cornea, making it more stable, holding its shape and focusing power better. These new cross-links help strengthen the cornea which stops the thinning process and further loss of vision.

Can CXL be performed for everyone with keratoconus?

During your consultation, we will determine if CXL might an option for you. Our practice offers a complimentary, no-touch, painless screening test to see whether CXL might help you.

Should your relatives be tested?

As you may know, keratoconus is a condition that often runs in families, so it’s important to arrange a screening with Dr. Scheno for all family members of patients with keratoconus.

How effective is CXL?

Many research studies have shown that it may prevent further vision loss in over 95% of patients.

Is CXL like LASIK?

No. LASIK is a procedure that reduces or, in some cases, may even eliminate the need for glasses or contact lenses by removing corneal tissue. The CXL treatment does not remove tissue. The purpose of CXL is to prevent further deterioration of vision for most patients and to potentially improve vision. LASIK can sometimes result in a keratoconus like condition called Post-LASIK Ectasia.

Can CXL prevent the need for corneal transplant?

Many studies have shown that CXL can often delay or prevent the need for a transplant and allow patients to wear contact lenses or glasses more comfortably and safely again.

Can a corneal transplant be done after CXL?


Can I have CXL if I already had a corneal transplant?


In some cases it can be performed after corneal transplantation.

What’s the difference between a corneal transplant and CXL?

CXL is an in office procedure that does not involve incisions into the eye. It is a relatively non-invasive procedure that is done with vitamin drops and light. Corneal transplants, in contrast, are performed in an operating room, involving incisions into the eye and a lifelong risk of rejection of the corneal tissue.

How long does CXL treatment last?

Based on CXL study results over more than a decade, the beneficial effects of CXL appear to last for many years and there is some evidence that this strengthening effect may be permanent.

Is CXL new?

Corneal collagen cross-linking has been performed since the late 1990's. The safety profile of CXL has been very positive in numerous studies throughout the world. CXL procedures are now routinely performed on patients as young as 10 years old to prevent the development of keratoconus.

Does CXL need to be repeated?

In many studies, the majority of patients responded to a single vitamin B2 and UVA light treatment and did not need to have the procedure repeated. CXL can often be repeated when treatment is not effective.

How is CXL performed?

The CXL treatment is an outpatient procedure performed in the doctor’s office using only numbing eye drops and a mild sedative like a Valium tablet. You’ll need to lie flat on your back in a reclining chair and look up at a soft blue light during the treatment. The epithelium, a thin layer of clear, protective tissue (like skin) that covers the cornea is removed for the CXL procedure. Next, vitamin B2 eye drops (riboflavin) are used in the eye and you will be asked to look at a special blue (ultraviolet) light while lying comfortably on a reclining chair. It’s generally easy to look at this light because your eyes are numb and we use drops so your eyes won’t feel dry.


What is the transepithelial (or epi-on) CXL technique?

In this less invasive CXL treatment, the surface skin layer (epithelium) of the cornea is not removed so the recovery is much faster than the traditional CXL technique. This less invasive technique can only be done on corneas that are thicker than 400 microns. Dr. Scheno will be able to determine if you might be a candidate for transepithelial CXL treatment This method is not currently FDA approved in the US..

Update: On April 11, 2018, an FDA clinicial trial of a new formulation of Vitamin B2 to be used in CXL treatment was announced and will hopefully eventually allow Dr. Scheno to perform CXL without removing the surface corneal layer in office. Stay tuned!

How long does the procedure take?

If two eyes are being treated at once, the procedure takes approximately an hour and a half. If only one eye is being treated at a time, the procedure takes approximately one hour.

Does the CXL procedure hurt?

No. The cross-linking procedure is painless. Anesthetic eye drops are used to avoid any discomfort during the procedure. Some patients have some discomfort after the procedure and Dr. Scheno can tell you whether you are or are not likely to do so.

Can I have one eye treated at a time?

Yes, Dr. Scheno will discuss the advantages and disadvantages of treating one eye or two eyes at a time.

When is the best time to have CXL?

As with most conditions, prevention is better than treatment. The best time to treat keratoconus is before astigmatism has become severe and vision has been lost. This does not mean that people with very poor vision from keratoconus cannot be helped by CXL. However, the results of CXL for patients with advanced keratoconus have not been as good as for patients with early disease.

Do I have to stop wearing contacts before having CXL?

We recommend that you stay out of contact lenses for a week or two if possible before your consultation visit to see if you might benefit from the CXL procedure. This can vary based on how difficult it is for you to see without your contacts. We often suggest patients not wear their lenses for a week before their CXL procedure.

When can I resume wearing contact lenses?

Most patients can return to wearing contact lenses after about a month following the cross-linking procedure depending on whether you are a candidate for trans-epithelial CXL. Your surgeon will determine how long this might take in your case.

Will I need new glasses or contacts after CXL?

Because cross-linking often improves vision, patients find that their old contacts or glasses are too strong for them and they need to be refit with new, glasses and/or contact lenses. Most of the time, patients can wear their old glasses until several months after the procedure when their doctor will prescribe new ones. Because the effects of CXL occur slowly, patients don’t generally have to change their glasses very often.

When will I notice any improvement in my vision after CXL?

With the traditional CXL procedure, most patients find that immediately after the cross-linking treatment, their vision is actually worse than it was before the procedure. This usually goes on for roughly 3-6 weeks. Patients may start to notice positive effects 4-8 weeks after the procedure and may experience major improvement in vision at least 3-6 months after the procedure. In some studies patients’ vision and astigmatism were still continuing to improve five years after the cross-linking procedure so visual improvement is a long process. With the less invasive trans-epithelial CXL, some patients found their vision improved as early as several weeks after treatment.

When can I exercise and return to my usual activities after CXL?

We want to help you be able to work or do other things you need and want to do as quickly as possible. Based on the type of CXL procedure, your doctor can tell you when you can return to your usual activities. With traditional CXL, most people can usually do so after about a week. With transepithelial CXL, most people return to their usual activities the next day.

Does insurance cover CXL treatment?

Currently this procedure is not covered by insurance although that is slowly changing as some insurance carriers are starting to recognize the benefits of the novel treatment.

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