Corneal Cross-Linking

What is corneal cross-linking?

Corneal cross-linking (CXL) is a minor procedure that helps reinforce and strengthen your cornea. It’s a treatment for keratoconus and other corneal ectasias — a group of conditions that cause thinning and bulging of your cornea.

Corneal ectasia is progressive, which means it gradually worsens over time. As it progresses, it can damage your vision by changing the shape of your cornea. Corneal cross-linking stops this process.

What does corneal cross-linking do?

The term “cross-linking” refers to the collagen fibers that hold your cornea together. Collagen is the protein that provides structure to your cornea. Cross-linking is how collagen fibers bond together.

Corneal cross-linking stimulates collagen fibers in your cornea to form new bonds, using UV light and riboflavin as a photosensitizing agent. This fortifies the tissue to stop it from thinning and bulging.

Who can corneal cross-linking help?

Your provider might recommend corneal cross-linking if corneal ectasia is threatening to do permanent damage to your vision. Many conditions can cause corneal ectasia, leading to astigmatism, including:

• Keratoconus.
• Pellucid marginal degeneration.
• Terrien marginal degeneration.
• Post-surgical ectasia (following LASIK, PRK or corneal transplant surgery).

Researchers are also studying corneal cross-linking as a potential treatment for other corneal diseases. While the results aren’t in yet, it’s possible that in the future, corneal cross-linking may treat:

• Infectious keratitis.
• Bullous keratopathy.
• Myopia.

Who shouldn’t have corneal cross-linking surgery?

Corneal cross-linking might not be a good idea for you if you have:

• Severe corneal thinning.
• Severe corneal scarring or clouding (opacification).
• A history of ocular herpes.
• An autoimmune disease.

Is corneal cross-linking surgery?

An ophthalmologist performs the corneal cross-linking procedure. Ophthalmologists are eye surgeons, and corneal collagen cross-linking is technically an eye surgery. But only a small part of it is surgical.

That part involves separating the top layer of your corneal tissue, called your epithelium, from the rest of your cornea. Surgeons do this so the treatment can penetrate to the deeper layers of your cornea.

Epi-off vs. Epi-on

In the original U.S. Food and Drug Administration (FDA)-approved version of the corneal cross-linking procedure, surgeons remove the epithelium entirely. This epithelial-off (“epi-off”) method has been proven effective by research. There are no epithelial-on protocols approved in the U.S.

How do I need to prepare for the corneal cross-linking procedure?

Corneal cross-linking is an outpatient procedure that you can have in your eye care provider’s office. You can go home the same day. You don't need to prepare, except to have someone else drive you home.

What happens during corneal cross-linking?

During the procedure, your ophthalmologist will:

• Numb your eye with anesthetic drops.
• Either remove or loosen the top layer of your cornea (epithelium).
• Apply riboflavin eye drops (vitamin B2) and allow them to sink in for about 30 minutes.
• Direct a beam of focused UV light onto your cornea for about 30 minutes.
• Apply antibiotic eye drops and steroid eye drops.
• Cover with a temporary contact lens and bandage.

How does corneal cross-linking work?

Corneal cross-linking uses riboflavin as a photosensitizer to help absorb the UV light and produce a photochemical reaction. This reaction helps form new bonds between collagen fibers in your cornea.

How long does corneal cross-linking take?

The whole procedure takes about 60 minutes. You can go home afterward. Your temporary contact lens and bandage will stay on for about a week. You may also continue to use steroid eye drops.

How painful is corneal cross-linking?

Postoperative pain can be mild to severe. You’ll have prescription eye drops to make you more comfortable. Don’t hesitate to use them or to speak up to your provider if they aren’t helping enough.

What are the benefits of corneal cross-linking?

Corneal cross-linking is the only procedure that can stop the progression of corneal ectasia. It can prevent more serious complications of corneal ectasia, like corneal hydrops and the need for corneal transplantation.

What is the success rate of corneal cross-linking for corneal ectasia?

Most research has focused on corneal cross-linking for keratoconus specifically. But it’s reasonable to assume that success rates for other types of corneal ectasia are similar. These rates are around 95%.

What are the risks of corneal cross-linking?

Risks of surgery include:

• Infection.
• Scarring.
• Permanent clouding of your vision (corneal haze).

These complications are rare.

Can corneal cross-linking worsen your vision?

Your vision will worsen before it gets better. Corneal haze (burring or clouding) typically lasts a few weeks to a few months after the procedure. In a small percentage of people, it can be permanent.

The effects of corneal haze on your vision are similar to the effects that corneal ectasia would eventually cause if you didn’t treat it. Your provider would likely recommend a corneal transplant in either case.

How long does it take to heal from corneal cross-linking?

You’ll have a bandage on your eye for about a week, which is about how long it takes for the top layer of your cornea to grow back after removal. You may also continue to use steroid drops during this period.

Your vision will return gradually. During the first few weeks, you may experience:

• Mild eye irritation.
• A feeling like there’s something in your eye.
• Light sensitivity.
• Dry eye.
• Corneal edema (swelling).
• Blurred vision.

Your vision should stabilize in two to three months. At this point, you may need new glasses or contacts.

Some people experience a hazing or clouding effect on their vision (corneal haze) that occurs about three to six months after surgery. It’s usually temporary, but in up to 10% of people, it’s permanent.

When should I call my healthcare provider?

Let your healthcare provider know right away if you experience sudden vision changes while recovering from corneal cross-linking. Make sure to let them know if your medications aren’t relieving your pain.