Corneal Collagen Crosslinking

The cornea, which is the clear, front surface of the eye, has a round and smooth shape that follows the curvature of the eye. Cross-linkages between collagen fibers provide structural support for the cornea, keeping it equally curved in all directions and ensuring that light entering the eye is equally focused in all planes. Eye diseases such as keratoconus can make the corneal tissue thin and weak, causing the cornea to bulge out and take on an irregular shape. The abnormal cone shape characteristic of keratoconus can result in poor vision due to the eye’s inability to focus light to a single point. Corneal collagen cross-linking (CXL) is a technique that was first used to halt or slow the progression of keratoconus in 1998. CXL is now the most widely used procedure throughout the world to treat the progressive vision loss associated with keratoconus.

WHAT IS KERATOCONUS?

Keratoconus is the most common cause of localized corneal thinning, affecting approximately 1 in 750 Americans. This disease causes the cornea to become thin, weak, and irregular in shape, which can lead to astigmatism and nearsightedness. Normally, the cornea has a round, smooth shape. Eye disorders such as keratoconus can deteriorate collagen fibers in the eye, which collectively act as an anchor within the cornea, causing the cornea to bulge and take on a cone-like shape.

This irregular shape can distort and blur one’s ability to see clearly, and keratoconus sufferers may first require glasses, then contact lenses, and finally a corneal transplant as their vision loss progressively becomes worse.

WHAT IS ASTIGMATISM?

Astigmatism occurs when abnormal variations or disturbances in the shape of the cornea result in glare and poor vision. Instead of having a round and even shape, the cornea becomes less round and more irregular, like a football, in people who suffer from astigmatism. Nearsightedness and farsightedness are often secondary symptoms of astigmatism due to the eye’s inability to focus light rays to a single point.

WHAT DOES CXL DO?

Healthy corneas have cross-links between their collagen fibers, and these cross-links act as an anchor and help the cornea retain its round shape. Keratoconus diminishes the amount and strength of cross-linking in the cornea, which weakens and pushes the corneal structure outward. Corneal collagen cross-linking increases the number of cross-links in the cornea and adds strength and stability to the corneal tissue, which stops or slows the corneal thinning process and vision loss associated with keratoconus.

CAN CXL BE PERFORMED FOR EVERYONE WITH KERATOCONUS?

The minimum recommended age for CXL treatment is 12 years old. Additionally, the corneas cannot be too thin or scarred for the procedure. Your doctor will determine if CXL is right for you during a one-to-one consultation.

HOW EFFECTIVE IS CXL?

A number of clinical trials conducted around the world have shown that CXL can slow or halt further vision loss in more than 95% of patients and restore vision in 60% to 81% percent of patients.

IS CXL LIKE LASIK?

LASIK corrects vision problems and eliminates the need for visual aids such as glasses or contact lenses by removing damaged corneal tissue. The CXL treatment does not involve the removal of any tissues from the eye, and the purpose of the procedure is to stop further vision loss. CXL is not a cure for eye diseases such as keratoconus, but it may improve vision and allow patients to lower the strength of their eyeglasses prescription and wear softer, more comfortable contact lenses.

CAN CXL PREVENT THE NEED FOR A CORNEAL TRANSPLANT?

Several studies have shown that the strengthening effect of CXL can be permanent and may delay or completely prevent the need for a corneal transplant.

CAN A CORNEAL TRANSPLANT BE DONE AFTER CXL?

If CXL does not provide noticeable, lasting results for keratoconus symptoms, then a corneal transplant may be the next step in treatment.

CAN I HAVE CXL IF I ALREADY HAD A CORNEAL TRANSPLANT?

CXL is a viable treatment option after a corneal transplant. However, each patient’s individual candidacy would require an in-depth evaluation with an ophthalmologist.

WHAT’S THE DIFFERENCE BETWEEN A CORNEAL TRANSPLANT AND CXL?

Corneal transplantation is an invasive, surgical procedure that’s performed in an operating room and involves the lifelong risk of rejection by the corneal tissue. CXL is a minimally invasive, in-office procedure that does not require any surgical incisions or stitches. CXL is performed with Riboflavin vitamin eye drops and ultraviolet light, which requires a shorter and relatively painless recovery process in comparison to corneal transplantation.

HOW LONG DOES CXL TREATMENT LAST?

The benefits of CXL treatment can last for several years, and clinical studies have shown that the strengthening effect of the procedure may be permanent.

How is CXL performed?

A CXL treatment is performed in the doctor’s office using anesthetic eye drops and a mild sedative such as Valium to minimize discomfort. Patients are placed flat on their back in a reclining chair for their individual comfort and ease of application for the doctor. At the start of the procedure, the clear, protective surface cells of the cornea, also known as the epithelium layer, are gently removed from the cornea. Next, riboflavin eye drops are applied to the eye, and the patient is directed to look into a soft blue ultraviolet light for 15 to 30 minutes. Focusing on the light is relatively easy for most patients because the eyes remain numb, and the riboflavin drops also work to keep the eyes moist. A special contact lens that acts as a protective bandage is then inserted and patched over the eye, where it will remain for up to five days after the procedure.

HOW LONG DOES THE PROCEDURE TAKE?

The CXL procedure can be completed in one eye in approximately one hour. If both eyes are being treated, treatment time takes approximately an hour and a half.

DOES THE CXL PROCEDURE HURT?

Corneal collagen cross-linking is a painless procedure because there are no surgical cuts made into the eye. Anesthetic eye drops to minimize discomfort during the procedure. Some patients may experience mild redness, stinging, or dryness of the eyes, but these side effects should subside within a few days.

Can I have both eyes treated at a time?

Technically, yes, but we typically treat one eye at a time. For some patients, however, short-term blurring following the procedure may make treating one eye at a time impractical. Your doctor will discuss the advantages and disadvantages or treating one or both eyes and help you determine the best option for your individual circumstances.

WHEN IS THE BEST TIME TO HAVE CXL?

As with any disease or health concern, it’s best to seek treatment in the early phase of the condition. Patients should seek CXL treatment for keratoconus before astigmatism severely diminishes their vision. This does not mean that CXL is not effective for later stages of keratoconus, but the treatment has shown the most promise for patients in the earliest stages of the disease.

WILL I NEED NEW GLASSES OR CONTACTS AFTER CXL?

Some patients experience dramatic improvements in their vision following CXL treatment. So much so, that their previous visual aids become too strong for them, requiring an adjustment in their glasses or contact lens prescription. In most cases, patients can continue wearing their old glasses until their doctor prescribes a new pair several months after the CXL procedure. Due to the gradual effects of CXL, patients shouldn’t have to change their eyeglasses prescription very often.

WHEN WILL I NOTICE ANY IMPROVEMENT IN MY VISION AFTER CXL?

Most patients experience a short period of blurred vision that may be worse than it was before a traditional CXL procedure. This side effect can persist anywhere from three to six weeks following the procedure. Patients should experience noticeable improvements within four to eight weeks and major improvements over the course of three to six months following the procedure. Patients who undergo the less invasive transepithelial CXL procedure notice improvements in their vision as early as two to three weeks. Visual improvement following CXL treatment is a gradual and long process, and some clinical studies have shown that patients continue to experience positive changes in their vision up to five years after their initial cross-linking procedure.

WHEN CAN I EXERCISE AND RETURN TO MY USUAL ACTIVITIES AFTER CXL?

Your recovery and downtime period will depend on the type of CXL procedure you receive, but your doctor will determine when you can resume your normal work schedule and daily activities. On average, patients can resume their normal activities within five to seven days of a traditional CXL procedure, while most patients return to work or social activities the next day following a transepithelial CXL procedure.