Corneal Cross-Linking Surgery
What Is Corneal Cross-Linking Surgery?
The cornea (the clear, dome-shaped layer at the front of the eye) contains well-organized and layered collagen fibers that give the cornea its transparency and strength. In some eye conditions, with keratoconus being the most common of these, the cornea can become thin and weak, leading to a decrease in vision. Corneal collagen cross-linking is an in-office procedure that has been shown to prevent loss of vision in some progressive eye conditions. This blog offers some basic information about this vision-saving surgical procedure, how it works, and who is a good candidate.
What Is the Role of the Cornea?
The cornea is the clear window into the eye and serves two key functions. First, it protects the eye from harmful elements acting as a barrier against dirt, foreign matter, and bacteria. Second, the cornea focuses and bends light as it enters the eye allowing for sharp vision.
Structurally, the cornea is a strong, transparent tissue and consists of the following five layers:
- Epithelium: As the outermost layer of the cornea, the epithelium prevents particles from entering the eye.
- Bowman’s layer: This thin layer of collagen fibers helps reinforce the cornea.
- Stroma: This layer, composed of collagen fibrils, gives the cornea its dome shape. It is the largest of the cornea layers, accounting for about 90% of the cornea’s total thickness.
- Descemet’s membrane: This thin membrane attaches the endothelium to the cornea while allowing nutrients to pass between the stroma and endothelium.
- Endothelium: The endothelium is made up of a single layer of cells specifically designed to pump fluid from the cornea.
In a healthy eye, the cornea is dome-shaped and composed of strong collagen fibers. However, in some eye diseases the collagen fibers become thin and weak and the cornea begins to bulge out into the shape of a cone, which impacts the way light is refracted or bent within the eye. This results in blurry or distorted vision, along with light sensitivity.
Cross-linking surgery is a minimally invasive surgical procedure that uses a combination of eye drops and UV light to strengthen corneal collagen fibers and stabilize the cornea, helping it keep its proper shape and hence maintenance of sharp vision. The goal is to prevent vision from getting worse, rather than to reverse any distorted vision you may already have. Worldwide studies have shown corneal cross-linking can prevent the need for a corneal transplant later in life. In many cases, vision can be improved after cross-linking with the use of specialty contact lenses. Each patient is different and this option can be discussed with your physician.
In 2016, the U.S. Food and Drug Administration (FDA) approved epi-off corneal cross-linking. Cornea specialists at the Dean McGee Eye Institute (DMEI) participated in the studies that concluded corneal cross-linking was effective at slowing progression of disease, which led to the FDA’s approval. DMEI was one of the first academic centers to offer the procedure.
How Is Cross-Linking Surgery Performed?
Cross-linking surgery is performed on an outpatient basis and takes about two hours. It involves three general steps:
- After a mild oral sedative, numbing drops are placed on the surface of the eye, followed by gentle removal of the central corneal epithelium
- The placement of riboflavin (vitamin B2) eye drops on the cornea
- Shining ultraviolet A (UVA) light onto the cornea
The riboflavin eye drops are administered for about 30 minutes to ensure the cornea is well saturated. The UV light shines on the cornea for another 30 minutes with the riboflavin drops intermittently administered during this time. The combination of eye drops and UV light causes a chemical reaction that strengthens collagen fiber bonds in the cornea, otherwise known as corneal collagen cross-linking. Patients will leave the office with a protective band-aid contact lens over the cornea, which helps with pain and healing. Some patients require pain medication for the first few days after cross-linking.
Who Is a Good Candidate?
People with a documented history of progressive keratoconus – a condition in which the cornea takes on a cone shape due to thinning and weakness, which leads to vision loss – are the most common candidates for cross-linking surgery. Corneal cross-linking is the only effective treatment known to slow or halt the progression of keratoconus. Similar corneal conditions, such as pellucid marginal degeneration and post-refractive surgery corneal ectasia, can also be treated by corneal collagen cross-linking.
Cross-Linking Surgery Recovery
After corneal cross-linking, antibiotic eye drops are prescribed to prevent infection as well as steroid eye drops to treat post-operative inflammation. Vision may be blurry for several weeks after the procedure before returning to pre-procedure levels with this timeline varying by patient.
Vision can fluctuate during the first few months after cross-linking surgery. If you wear contact lenses or eyeglasses, your doctor will instruct you when to return to contact lens wear or when to be re-fit for a new contact lens or glasses prescription should your prescription change after the procedure. It is generally 2-3 months before new glasses or contact lenses are prescribed.
Are There Any Risks to Corneal Cross-Linking?
At DMEI, we encourage our patients to talk with their surgeon about any concerns ahead of time. While cross-linking is a safe procedure, no procedure is without some risk. Rarely, these can include a delay in healing of the epithelium, infection, scarring, severe eye pain or sudden vision loss. If you experience any of these symptoms, contact your doctor right away.
Corneal Cross-Linking Surgery at Dean McGee Eye Institute
At Dean McGee Eye Institute, we have a talented team of three cornea and external diseases specialists with years of experience performing corneal cross-linking surgery.
Browse our directory to learn more about our team or call 405.271.1092 or 800.787.9014 to schedule an appointment to see if you are a candidate for this procedure.
Who’s A Good Candidate for a Corneal Cross-Linking?
The best candidates for corneal cross-linking are those with documented disease progression of keratoconus. Your corneal specialist will discuss further details with you on whether or not you are a good candidate, as other factors, such as age, are important as well.
CXL is performed as an office visit without surgical incisions. Prior to the procedure, your eyes will be numbed using eye drops. The thin layer of the cornea, the epithelium, will be removed. This is known as “epi-off cross-linking”, which is the FDA-approved protocol. Riboflavin (Vitamin B2) is then applied to the cornea. After this, you will lie on your back in a chair as an ultraviolet light is used in combination with the riboflavin to trigger bonding (cross-linking) of collagen molecules in the cornea. A contact lens is placed on the cornea at the end of the procedure.
Currently, “epi-on cross-linking” is undergoing FDA trials. You may wish to talk to your DMEI cornea specialist to see what options are available for patients whose corneas are too thin for the epi-off protocol.
Are There Any Risks with Corneal Cross-Linking Surgery?
CXL has a low rate of risks or complications, but there are a few, including:
We encourage you to speak with your surgeon about possible side effects.
Preparing for a Corneal Cross-Linking
Your ophthalmologist will inform you of any steps to take prior to the procedure. You’ll also need to arrange for someone to drive you home after your procedure, as your eyesight will be affected.
Your vision may be blurry for a few days (up to a week) after the procedure, so you may want to adjust your work and home schedule accordingly. You can resume normal activities the very next day as long as your vision and eye comfort levels allow. The contact lens will be removed within a few days after the surgery. You will have to use eye drops afterward as directed by your cornea doctor. After a few weeks, we will check your vision again for any updates that might be needed to your glasses and/or contact lenses. Patients who wear contact lenses may cautiously return to contact lens wear as per the instructions of your cornea doctor.
Corneal Cross-Linking Surgery at Dean McGee Eye Institute
For 45 years, our corneal cross-linking surgeons at the Dean McGee Eye Institute have been at the forefront of surgical technology and techniques, including corneal cross-linking. Call 405.271.1095 or 800.787.9017 to schedule an appointment or search our directory to learn more about our corneal cross-linking surgeons.