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 special eye drops and ultraviolet A (UVA) light to make the tissues in your cornea stronger. That stops the bulge from getting worse.

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

The FDA approved corneal cross-linking for keratoconus in 2016. Right now, it’s the only treatment that can stop the condition from getting worse. And it may help you avoid a corneal transplant, which is major surgery.

What Happens During the Procedure?

corneal cross linking procedureYour 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.

Then, she’ll put in riboflavin (vitamin B2) eye drops, which allow your cornea to better absorb light.

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

The entire treatment takes about 30-60 minutes.

Types of Corneal Cross-Linking

There are two types: epi-off and epi-on. “Epi” is short for epithelium, a layer of tissue that covers your cornea.

The epi-off technique means your doctor removes the epithelium before she puts the drops in. Some experts believe that allows your eye to absorb the vitamins and light better. But it takes longer to recover and has more risks.

With epi-on, your epithelium is left alone. That means you’ll have no pain and a short recovery.

Doctors have debated which of these methods is better, but for now, the FDA has approved just the epi-off procedure.

Sometimes doctors can do epi-on procedures as “off-label” therapy, which means they do the treatment in a modified way or for another purpose than what it’s approved for.


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 will help you figure out if this treatment would help you.

How to Prepare

Your doctor might tell you not to wear contact lenses for a couple of weeks before your treatment. Also, ask her if there are any foods or medicines you should avoid during this time.

The day of the procedure, don’t wear eye makeup, perfume, or after-shave. You should be able to eat a light meal and drink fluids beforehand, though.

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’s Recovery Like?

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. 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.

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

With an epi-off procedure, your eyesight will get worse at first, but it should go back to normal within 6-12 months. You may be more sensitive to light and have poorer vision for 1-3 months after the surgery.

With epi-on, vision usually goes back to normal the next day.

The goal of corneal cross-linking is to slow your disease and prevent future vision problems, but it could also improve your eyesight over time.

The epi-off procedure prevents the cornea from bulging in about 62% of people who get it. About 60% notice slightly better vision, but about 33% had ongoing problems after 1 year.

The epi-on procedure prevents the cornea from getting worse in about 99% of people. There are usually no problems afterward.

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

Before you have the procedure, ask your doctor about your chances of having these issues.

Epi-on corneal cross-linking usually doesn’t have any side effects.

Other Uses for Cross-Linking

Scientists are studying whether corneal cross-linking could treat other eye problems, such as:

  • Post-LASIK ectasia (a weak cornea caused by LASIK surgery)
  • Corneal ulcers
  • RK (radial keratotomy) vision changes
  • Other conditions that affect the cornea

WebMD Medical Reference Reviewed by Brian S. Boxer Wachler, MD on October 12, 2017



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.”

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.”

American Society of Cataract and Refractive Surgery.

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