Corneal Collagen Cross-Linking: What Is It?

What_is_Corneal_Collagen_Cross-Linking

Corneal cross-linking (CXL) for the eye is a surgical treatment to treat conditions that affect the cornea, the transparent surface of the eye. This procedure strengthens the collagen fibers within the cornea to prevent further damage, stabilize the shape of the eye, and, in some cases, improve vision.

Who can Benefit from Corneal Cross-Linking?

Corneal cross-linking is most commonly used to halt the progression of keratoconus, but it may also be beneficial for other corneal conditions, such as corneal ectasia, whereas the cornea becomes too thin and begins to bulge.

Here are some people who may benefit from corneal cross-linking:

Normal_vs_keratoconus_cornea_diagram

How Does Corneal Cross-Linking Work?

Collagen is a protein that provides strength and structure to the cornea. In conditions like keratoconus, the collagen in the cornea becomes weak and less organized, causing the cornea to thin and bulge.

A photosensitizing agent, riboflavin drops (vitamin B2), is applied to the cornea. Riboflavin works as a “bridge” to strengthen the collagen structure, stabilizing the cornea and making it more resistant to further deformation.

The result is a stronger, more rigid cornea, which can help prevent the progression of keratoconus and other corneal thinning disease. 

Corneal_cross-linking_steps_illustration

Source: Boston Vision

What to Expect During the Corneal Cross-Linking Procedure

Corneal cross-linking is typically an outpatient procedure, meaning patients can go home the same day. Here’s what you can expect during the procedure:

  1. Numbing the Eye: Before the procedure begins, topical anesthetic eye drops will be applied to ensure that you are comfortable and pain-free during the treatment.
  2. Riboflavin Application: The ophthalmologist will apply riboflavin (vitamin B2) drops to the cornea. 
  3. UV Light Exposure: The cornea will be exposed to ultraviolet (UV) light for a set period, around 30 minutes. The UV light activates the riboflavin and initiates the collagen cross-linking process.
  4. Bandage Contact Lens Application: This helps the cornea to heal. 
  5. Post Operative Care: Antibiotic and steroid drops will be given to help your eye heal.

UV_light_applied_during_corneal_cross-linking

Source: Cleveland Clinic

Benefits of Corneal Cross-Linking for the Eye

Corneal cross-linking offers several benefits, particularly for individuals with keratoconus and other corneal conditions:

  1. Prevents Disease Progression: It can prevent further vision deterioration and might reduce the need for a corneal transplant.
  2. Minimally Invasive: Unlike a corneal transplant, collagen cross-linking is a minimally invasive procedure with a relatively quick recovery time. Most patients return to their normal activities within a few days to weeks.

If you or someone you know is dealing with corneal disease, it’s important to talk to an ophthalmologist about the benefits and risks of CXL. With early detection and appropriate treatment, you can help protect your vision for years to come.

The cornea specialists available in OasisEye Specialists include Dr Vanitha Ratnalingam who is based in Kuala Lumpur and Penang; and Dr K John Mathen who is based in Kuala Lumpur. 

FAQs

During the procedure, you will receive numbing eye drops, so there is little to no pain.

The main goal is to halt progression, not necessarily improve vision.
However, some patients experience mild flattening of the cornea, which can lead to slight vision improvement over time.

No. CXL stabilizes the cornea and slows or stops further worsening but does not reverse keratoconus. Additional treatments, like contact lenses, glasses, or intracorneal ring segments, may still be needed.

Common side effects include:

  • Temporary blurry vision.
  • Eye discomfort or dryness.
  • Light sensitivity.

Rare but serious risks include:

  • Infection.
  • Corneal haze or scarring.
  • Delayed healing.

Yes.

  • No rubbing the eyes.
  • Avoid swimming, eye makeup, and dusty environments until the doctor clears you.
  • Use prescribed antibiotic and anti-inflammatory drops exactly as instructed.

Yes. However, the procedure can stabilize your condition and prevent the need for a corneal transplant.

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What is Corneal Transplant

A corneal transplant, also known as keratoplasty, is a surgical procedure in which a damaged or diseased cornea is replaced with a healthy cornea from a donor. The cornea is a transparent tissue located at the most front of the eye which helps focus light and contributes to clear vision.

WHO NEEDS A CORNEAL TRANSPLANT?

Several conditions can affect the cornea, leading to vision impairment that cannot be corrected by glasses, contact lenses, or other non-surgical treatments. Some of the common reasons for needing a corneal transplant include:

  • Keratoconus: Cornea becomes thinner, steeper and bulges outward into a cone shape.
  • Fuchs’ dystrophy: A disease which builds up fluid and results in corneal swelling.
  • Corneal scarring (due to injury or infection).

TYPES OF CORNEAL TRANSPLANT

1. Full-thickness (Penetrating Keratoplasty): The entire thickness of the cornea is replaced. This type of transplant is done when the damage affects both the front and inner cornea.

Full-thickness_corneal_transplant_(PKP)_graphic_replacing_all_corneal_layers

2. Partial-thickness (Lamellar Keratoplasty): Only the front and the middle of the cornea is replaced. This may be done for conditions affecting only the outer layers of the cornea, such as certain corneal dystrophies.

Diagram_of_DALK_procedure_replacing_outer_corneal_layers_in_a_partial-thickness_transplant

3. Endothelial Keratoplasty: A newer and minimal invasive type of transplant that replaces only the inner layer of the cornea (the endothelium).

Illustration_of_DMEK_corneal_transplant_showing_thin_inner_layer_replacement

THE PROCEDURE

Here’s an overview of how the surgery works:

  1. Local anesthesia: Before the surgery, eye drops will be instilled to numb the eye.
  2. Removal of the Damaged Cornea: The surgeon will remove the host’s cornea using a special surgical instrument, leaving a small rim of tissue to hold the donor cornea in place.
  3. Donor Cornea Placement: Surgeons use fine sutures or air bubbles to attach the donor tissue to the eye. The sutures will be left in place for weeks to months to allow for proper healing.
  4. Recovery and Follow-up: The healing process can take several months, during which time the patient will need to attend follow-up appointments to ensure the transplant is successful and to monitor for complications.

POSSIBLE COMPLICATIONS

Graft rejection occurs when the body’s immune system sees transplanted tissue as something that shouldn’t be there and tries to get rid of it. This can occur in 3 out of every 10 patients transplanted.

Warning signs of your body trying to reject your cornea transplant include:

  • Redness
  • Sensitivity to light
  • Hazy vision
  • Eye pain

Should you experience such symptoms after a transplant, see your corneal surgeon immediately. Your ophthalmologist might be able to stop the rejection with medicine.

CONCLUSION

If you or someone you know is struggling with vision problems due to corneal issues, a consultation with an ophthalmologist can help determine if a corneal transplant might be a viable solution. 

The corneal surgeons available in OasisEye Specialists include Dr Vanitha Ratnalingam who is based in Kuala Lumpur and Penang; and Dr K John Mathen who is based in Kuala Lumpur.

FAQs

Donor corneas are sourced from deceased human donors, carefully screened and preserved by certified eye banks. At OasisEye Specialists, donor tissue is mainly obtained from Sri Lanka and the United States, both of which have internationally recognized eye donation systems.

The estimated cost at OasisEye Specialists is approximately RM15,000 to RM20,000 per eye. Costs may vary based on individual clinical needs.

Typically, the procedure takes about 1 to 2 hours, depending on the type of transplant.

Recovery varies but often takes several months to a year for full vision stabilization. Regular follow-ups are essential.

Vision usually improves gradually over weeks to months after surgery. Sometimes, additional procedures like glasses, contact lenses, or refractive surgery may be needed for best results.

Usually, surgery is done on one eye at a time to reduce risk.

With proper care, many grafts last 10 to 20 years or more, though some may fail earlier.

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Types of Corneal Ulcer

Corneal ulcer is an inflammation of the cornea secondary to infection. It will cause red eyes, pain, excessive tearing, blurred vision and light sensitivity. Corneal ulcer can be caused by bacteria, viruses, fungi and parasites. If left untreated or if infection is severe, corneal ulcer can lead to permanent damage of vision.

Bacterial keratitis

Bacterial infections are the most common cause of corneal ulcer. Most of the time Pseudomonas Aeruginosa, Staphylococcus species and Streptococcus species are responsible for this type of infection. Bacterial keratitis can develop quickly. There is a high risk of getting infection from long hours of wearing contact lenses or not taking care of them correctly. Thus, proper care of contact lenses will reduce the risk of developing a corneal infection.

Close-up_of_an_eye_with_a_severe_corneal_ulcer,_showing_a_white_cloudy_spot_and_redness.

Fungal keratitis

Improper use of contact lenses or steroid eye drops can lead to fungal infection. A corneal injury that results in plant material like being hit by a tree branch also will cause fungal keratitis which is mostly due to Fusarium or Aspergillus species. Candida species will typically cause keratitis in the eye with preexisting ocular surface disease or eyes that have recently been treated with topical steroid. Fungal keratitis is devastating, hard to treat and remains a common cause of blindness in tropical countries.

Eye_with_herpes_simplex_keratitis,_featuring_a_branching_corneal_lesion_and_redness.

Herpes simplex keratitis

Herpes keratitis is a viral infection caused by herpes simplex virus. It may cause recurring attacks and be very contagious when contact with someone who has the virus. After primary infection, the virus lies in a dormant state, living in the nerve cell of the eye. It can be triggered by stress, trauma, fever or certain medications.

Acanthamoeba keratitis

Lastly, parasitic infection caused by Acanthamoeba is a rare, vision threatening corneal ulcer. Acanthamoeba is a microscopic, single-cell living organism and can be found in freshwater and soil. People who wear contact lenses develop higher risk of getting Acanthamoeba keratitis when they clean lenses with tap water, swimming while wearing contacts or contact with contaminated water. Early diagnosis and treatment of Acanthamoeba keratitis is essential to prevent loss of vision.

An ophthalmologist will be able to assess your eye and diagnose the type of corneal ulcer/infectious keratitis you have. All these conditions may cause severe pain and impaired vision. Therefore, corneal ulcer/infectious keratitis may need serious medical attention and should be treated immediately to prevent the conditions from worsening.

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