Corneal Collagen Cross Linking
Corneal Collagen Cross-Linking (CXL) is a technique that was ﬁrst 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 ﬁbers 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 99% of patients. As well, it often 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 corneal 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 ﬁt 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. Following corneal transplantation, some patients may still experience progressive corneal thinning and weakening. If there is evidence of corneal weakening in a patient who has a corneal transplant, CXL can be performed, and it will stabilize and often improve the corneal shape and vision.
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 2 decades, the beneﬁcial effects of CXL and corneal strengthening effect appear to be permanent.
Is CXL new? Corneal collagen cross-linking has been performed since 1999. The results and safety proﬁle 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 2016, Epithelial-Off CXL got FDA approval in the United States. CXL procedures are now routinely performed on patients as young as 8 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 and light CXL treatment and did not need to have the procedure repeated. CXL can typically be repeated when the initial treatment does not completely arrest the progression of keratoconus.
How is CXL performed? The CXL treatment is an outpatient procedure performed in the doctor’s office using only numbing eye drops and an optional mild oral sedative (Valium tablet). You will need to lay ﬂat on your back in a reclined chair for the treatment process. A vitamin eyedrop solution (riboﬂavin) 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? The procedure takes approximately an hour and 15 minutes, and both eyes can have the procedure performed at the same time.
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, the prevention of a problem is better than the treatment of a problem. The best time to treat keratoconus is before astigmatism has become severe and vision has been lost. This is because the CXL procedure can stop keratoconus from progressing. Patients with more advanced keratoconus can benefit as well, as the procedure will help prevent further vision loss. As well, many patients can often experience some improvement in vision over months to years after the CXL procedure. So in general, the sooner that keratoconus can be treated with CXL, the better.
If CXL 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 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 ﬁnd that their old contacts or glasses are too strong for them and that 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 (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 this with you when you can return to your usual activities. With traditional CXL, most people can usually do so after 5-7 days. With transepithelial (Epi-on) CXL, most people return to their usual activities the next day.
I don’t live in South Florida, but would like to move forward with CXL, what should I do? We treat many, many patients from all around the US, as well as other parts of the world. Please click here if you are an Out of Town Patient.
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.