Cross Linking (CXL) Strengthening of the Cornea in the US

What is Cross Linking (CXL)?

What is Cross-Linking or CXL?

Corneal Collagen Cross-Linking (CXL) is a technique that was ?rst used in 1998 to treat patients with a corneal disease called keratoconus.  A cornea with keratoconus (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.  The purpose of CXL is to stop the thinning and steepening of the cornea and prevent further deterioration of vision.  It is believed that by activating absorbed riboflavin with ultraviolet light, new shortened and thickened collagen crosslinks are formed. This strengthens corneal collagen and makes the collagen resistant to further thinning and deformation.

What is keratoconus? 

Keratoconus is a common disease that occurs in approximately 1 in 750 Americans.  With this condition, the cornea becomes weak, progressively thinner, and irregular in shape which can cause high levels of astigmatism.  Instead of a normal, relatively round shape resulting in clear vision, a cornea with keratoconus can become cone shaped.  This can interfere with the ability to see clearly.  Keratoconus patients often require glasses first, then contact lenses, and, if the condition progresses to a severe level, a corneal transplant may be required.

What is astigmatism? 

Astigmatism means that the front surface of the eye (the cornea or clear window in front of the eye) is less round and more irregular in shape so the image won’t focus clearly on the retina in the back of the eye. This can result in poor vision and glare.

What does CXL do? 

Normal corneas have crosslinks between collagen ?bers that keep it strong and able to retain its normal shape.  With keratoconus, the cornea becomes weak, because there are 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, able to hold its shape, and focusing power better.

Can CXL be performed for everyone with keratoconus? 

During your consultation, we will determine if CXL might be an option for you.  Our practice offers a complimentary, no-touch, painless screening test to see whether CXL might help you.
Should your family members/relatives be tested?  As you may know, keratoconus is a condition that often runs in families, so it’s important to arrange a screening for all family members of patients with keratoconus.  If caught early, there is a good chance that CXL can halt the progression of keratoconus and prevent the need for uncomfortable contact lens wear and/or corneal transplant.

How effective is CXL? 

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

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 CXL procedure thickens and strengthens the cornea tissue. The purpose of CXL is to stop the thinning and steepening of the cornea and prevent further deterioration of vision.  Patients will typically require a lower eyeglass prescription or can have an easier time being ?t with contact lenses.

Can CXL prevent the need for a corneal transplant? 

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

Can a corneal transplant be done after CXL? 

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

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

Each patient and each patient’s eyes are different.  In some cases CXL 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 surgical incisions into the eye or stitches.  It is a relatively non-invasive procedure that is done with vitamin 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 CXL treatment last? 

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

Is CXL new? 

Corneal collagen cross-linking has been performed since 1999.  The results and safety pro?le of CXL 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.  As of 2017, CXL got FDA approval in the United States.  CXL procedures are now routinely performed on patients as young as 10 years old in Europe to prevent the development of keratoconus.

Does CXL need to be repeated? 

In many studies, the majority of patients responded to a single vitamin and light CXL 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 oral sedative (Valium tablet). You will need to lay ?at on your back in a reclined chair for the treatment process.  A vitamin eyedrop solution (ribo?avin) will be placed into the eye.  After the application of the riboflavin eye drop solution your doctor will examine your cornea.  Next, you will be asked to look up at a light during the treatment.  It is generally easy to look at this light because your eyes are numb; rewetting drops will be applied during the treatment. After the light is applied your doctor will examine your cornea and the treatment is complete.

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.

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 your doctor 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 CXL? 

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 CXL.  However, the results of CXL for patients with advanced keratoconus have not been as good as for patients with early stages of the disease.
If CXL works for me and stops my vision from getting worse, can I have laser vision correction or Intacs afterwards? 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 CXL procedure.

Do I have to stop wearing contacts before having CXL?

We often suggest patients not wear their lenses for 3-5 days before their CXL evaluation and procedure.  This can vary based on how difficult it is for you to see without your contacts.

When can I resume wearing contact lenses?

Most patients can return to wearing contact lenses 2 to 6 days after having the cross-linking procedure.  Your doctor 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 ?nd that their old contacts or glasses are too strong for them and that they need to be re?t 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 ?nd 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 after the procedure.  In some studies, patients’ vision and astigmatism were still continuing to improve ?ve years after the cross-linking procedure so visual improvement is a long process.  With the less invasive trans-epithelial (epi-on) 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 will discuss with you when you can return to your usual activities.  With traditional CXL, most people can usually do so after 5-7 days.  With trans- epithelial (Epi-on) CXL, most people return to their usual activities the next day.

For more information about Corneal Crosslinking (CXL), keratoconus, and/or our diagnostic screenings and treatments, please call our practice at 305-598-2020 to schedule an evaluation.  You can also visit our Keratoconus site to learn more about Corneal Collagen Cross Linking.  At your visit, you will learn if you are a candidate for this treatment and will be able to discuss your medical history with the physician.


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