Corneal Cross-Linking (CXL)

Treating Keratoconus With Corneal Cross-Linking

Corneal collagen cross-linking is a technique that was first used in 1998 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 their normal round shape, corneas with keratoconus can bulge forward into the shape of a cone causing poor vision. Corneal cross-linking is now being performed for patients with this condition in approximately 450 centers throughout the world.

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What does corneal cross-linking do?

Normal corneas have crosslinks between their collagen fibers that keep them strong and able to retain their normal shape. In keratoconus, the cornea is weak with too few cross-links or support beams. This weakened structure allows the cornea to bulge outwards. 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.

Should your relatives be tested for keratoconus?

As you may know, keratoconus is a condition that often runs in families. Therefore, it’s important to arrange a screening for all family members of patients with keratoconus. If caught early, there is a good chance that corneal cross-linking can halt the progression of keratoconus and prevent the need for uncomfortable contact lens wear and/or corneal transplant.

How effective is corneal cross-linking?

Many research studies have shown that cross-linking may prevent further vision loss in over 95% of patients and improve vision in 60-81% of patients treated.

Is corneal cross-linking 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 cross-linking treatment does not remove tissue. The purpose of cross-linking is to prevent further deterioration of vision for most patients and to potentially improve vision. Patients will typically require a lower eyeglass prescription or can have an easier time being fit with contact lenses.

Can corneal cross-linking prevent the need for corneal transplant?

Many studies have shown that cross-linking can often prevent the need for a corneal transplant and allow patients to wear contact lenses or glasses more comfortably and safely again.1-11

Can a corneal transplant be done after cross-linking?

If cross-linking does not prevent the need for a corneal transplant, then a corneal transplant can generally be performed.

Can I have corneal cross-linking if I already had a corneal transplant?

Each patient and each patient’s eyes are different. In some cases, corneal cross-linking can be performed after corneal transplantation.

What’s the difference between a corneal transplant and cross-linking?

Corneal cross-linking is an in-office procedure that does not involve surgical incisions into the eye or stitches. It is a relatively non-invasive procedure that is done with Photrexa Viscous eye drops and light. Corneal transplants are performed in an operating room, involving incisions into the eye and a lifelong risk of rejection of the corneal tissue.

How long does corneal cross-linking treatment last?

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

Is corneal cross-linking new?

Corneal collagen cross-linking has been performed since 1999. The results and safety profile of corneal cross-linking have been very positive in numerous studies throughout the world. In fact, by September of 2006, CXL had been approved by all 25 European Union nations. Corneal cross-linking procedures are now routinely performed on patients as young as 10 years old in Europe to prevent the development of keratoconus.

Does cross-linking need to be repeated?

In many studies, the majority of patients responded to a single vitamin and light corneal cross-linking treatment. This means they did not need to have the procedure repeated. Corneal Cross-Linking can often be repeated when treatment is not effective.

How is corneal cross-linking performed?

The corneal cross-linking treatment is an outpatient procedure performed in the doctor’s office. The treatment uses 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 cross-linking procedure. Next, vitamin eye drops (Photrexa Viscous eye drops) 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.

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 corneal cross-linking 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. Your surgeon can tell you whether you are or are not likely to do so.

Can I have one eye treated at a time?

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

When is the best time to have corneal cross-linking?

As with most conditions, prevention of a problem is better than treatment of a problem. 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 corneal cross-linking. However, the results of corneal cross-linking for patients with advanced keratoconus have not been as good as for patients with early disease.

If corneal cross-linking works for me and stops my vision from getting worse, can I have laser vision correction or Intacs afterward?

Some patients may be able to have an excimer laser treatment (PRK) or Intacs to improve their vision without glasses after they have healed from the cross-linking procedure.

Do I have to stop wearing contacts before having the procedure?

We recommend that you stay out of contact lenses for a week or two if possible before your consultation visit. We recommend this to see if you might benefit from the investigational corneal cross-linking 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 3 days before their cross-linking procedure.

When can I resume wearing contact lenses after a CXL Procedure?

Most patients can return to wearing contact lenses 2 to 6 weeks after having the cross-linking procedure depending on whether you are a candidate for transepithelial corneal cross-linking. 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. If this is the case for you, you’ll 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 a major improvement in vision at least 3-6 months after the investigational 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 transepithelial 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. Your doctor can tell you when you can return to your usual activities. With traditional CXL, most people can usually do so after 5-7 days.

Does insurance cover CXL treatment?

Some insurances cover corneal cross-linking. Your vision counselor will help you to submit to your insurance and will notify you of coverage and out-of-pocket responsibilities.


This prescription insert provides a unique new option to improve a patient’s vision and possibly defer a corneal transplant. Intacs are indicated for the correction of nearsightedness and astigmatism for patients with keratoconus, where contact lenses and glasses no longer provide suitable vision.

For those keratoconic patients who are contact lens intolerant, Intacs prescription inserts offer a less threatening option than a corneal transplant. Most physicians would prefer to delay a corneal transplant – to make it the option of last resort. Intacs prescription inserts make this a possibility by improving functional vision, and possibly delaying the need for a corneal transplant.

The goal of the Intacs procedure is to provide the keratoconic patient with the ability to achieve improved functional vision with contact lenses or glasses in some cases without them. In the patients who later had a corneal transplant after having the Intacs procedure, their transplants were completed without any complications. Talk to your physician today to see if Intacs are right for you.

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