What Is Corneal Cross-Linking?

Corneal cross-linking is a treatment for an eye problem called keratoconus.

In this condition, the front part of your eye, called the cornea, thins out and gets weaker over time. This makes it bulge into a cone shape, which can distort your vision and make it hard to see. 

In corneal cross-linking, doctors use eyedrop medication and ultraviolet (UV) light from a special machine to make the tissues in your cornea stronger. The goal is to keep the cornea from bulging more.

It’s called “cross-linking” because it adds bonds between the collagen fibers in your eye. They work like support beams to help the cornea stay stable.

Corneal cross-linking is the only treatment that can stop progressive keratoconus from getting worse. And it may help you avoid a corneal transplant, which is major surgery.

What Happens During the Procedure?

corneal cross linking cxl

Your doctor can do the corneal cross-linking procedure in her office.

First, you’ll get drops that numb your eyes and a medicine to calm you if needed.

Then, your doctor will put in riboflavin (vitamin B2) eyedrops, which allow your cornea to better absorb light. It takes about 30 minutes for the drops to soak into your cornea.

Then, you’ll lie back in a chair and look up at a light. You shouldn’t feel any pain during the procedure because your eyes will be numb.

The entire treatment takes about 60-90 minutes.

Types of Corneal Cross-Linking

There are two types: epi-off and the experimental epi-on. (“Epi” is short for epithelium, the outer layer of the cornea.)

The epi-off technique means your doctor removes the epithelium before she puts the drops in. Many studies have found that this technique works well, but it may also raise your risk of infection and can lead to clouding in your cornea.

With epi-on, your doctor loosens your epithelium with eyedrops or a sponge before she puts the eyedrops in. There are fewer side effects.

Doctors have debated which of these methods is better.


Who Should Get Corneal Cross-Linking?

Corneal cross-linking works best if you’ve recently been diagnosed with keratoconus.

The procedure doesn’t reverse cornea changes that have already happened -- it just keeps them from getting worse.

Your doctor can let you know if this treatment would help you.

How to Prepare

The day of the procedure, don’t wear eye makeup, perfume, or after-shave. In most cases, you’ll be able to eat a light meal and drink fluids beforehand.

You’ll also need someone to drive you home after your procedure since your eyesight will be affected.

Follow your doctor’s instructions carefully.

What Happens Afterward?

It depends on the type of procedure you have.

With the epi-on procedure, recovery is usually painless. You’ll be able to go about your regular activities as soon as the next day, including wearing contacts.

If you had an epi-off procedure, you’ll probably have a fair amount of pain for several days or more after the numbing drops wear off.  It’s important not to rub your eyes. You’ll need pain medications. It will be about 4-10 days before you’re back to your usual routine, but it could take several weeks, since the epithelium needs time to heal. If the contact lens falls off, call your doctor ASAP.  Don’t try to put it back in yourself.

You’ll probably need to wear a soft contact lens for about a week after epi-off surgery and use antibiotic and steroid eye drops for up to 2 weeks. You can usually start wearing your regular contacts again after about 2-4 weeks, but your vision will change over 3-6 months.

Your Vision After Corneal Cross-Linking

After an epi-off cross-linking procedure, your eyesight will be blurry for weeks to months. With epi-on, you vision is typically back to baseline within a day. You may notice changes in your vision as your cornea heals. You may be more sensitive to light and have poorer vision for about 1-3 months after the surgery.

The goal of corneal cross-linking is to slow your disease and prevent future vision problems, but in some cases, your eyesight may get better over time.

Once you’ve had corneal cross-linking, you might need new glasses or contacts.



Like most surgeries, epi-off corneal cross-linking can sometimes cause problems, such as:

  • An eye infection
  • Eye pain or swelling
  • Damage to the cornea or epithelium
  • Blurred vision, hazy vision, or other vision problems

Such problems are rare with epi-on cross-linking. Before you have the procedure, ask your doctor about your chances of having these issues.

WebMD Medical Reference Reviewed by Brian S. Boxer Wachler, MD on January 08, 2020



National Keratoconus Foundation: “About Keratoconus Eye Disease,” “How Keratoconus is Treated,” “Crosslinking Update: Understanding what FDA Approval Means.”

Mayo Clinic: “Keratoconus: Diagnosis and Treatment.”

University of Miami Health System: Bascom Palmer Eye Institute: “Corneal Cross-Linking.”

American Academy of Ophthalmology: “Corneal Collagen Cross-linking Approved to Treat Keratoconus in U.S.,” “Ectasia After Lasik,” “Keratoconus Treatment.”

American Optometric Association: “FDA approves first corneal cross-linking system for treatment.”

University of Michigan Kellogg Eye Center: “Corneal Cross-Linking (Collagen Cross-Linking).”

Middle East African Journal of Ophthalmology: “Corneal Collagen Cross-Linking.”

Johns Hopkins Medicine: “Corneal Collagen Cross-linking at the Johns Hopkins Wilmer Eye Institute.”

American Keratoconus Association: “Cornea Collagen Crosslinking with Riboflavin.”

MedStar Georgetown University Hospital: “Corneal Cross-linking.”

USC Roski Eye Institute: “Keratoconus and Corneal Cross-Linking (CXL) Treatment.”

Journal of Ophthalmology: “Complications of Corneal Collagen Cross-Linking.”

FDA: “Riboflavin Ophthalmic Solution/KXL System for the Treatment of Progressive Keratoconus or Corneal Ectasia Following Refractive Surgery.”

NIH National Eye Institute: “Facts About the Cornea and Corneal Disease.”

Medscape: “Corneal Crosslinking: Is Using an Epithelium-On Technique Effective?”

University of Chicago Department of Ophthalmology and Visual Science: “Corneal Cross-linking FAQs.”

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