Collagen Crosslinking

colorful illustration of collagen fibers

Collagen crosslinking (CXL) is a relatively new procedure used to treat patients with keratoconus. Keratoconus is a thinning of the corneas which causes them to form a cone shape and bulge outwards. Many countries outside the U.S. use CXL, but the procedure hasn’t yet received FDA approval. However, since 2008, many people with keratoconus have participated in nationwide clinical trials in the U.S.

The Idea

Strong crosslinks between collagen fibers help healthy, normal corneas retain their shape. However, people with the thin corneas characterized by keratoconus lack adequate collagen support beams. The idea behind CXL is to strengthen these beams, to stabilize the corneas, allow them hold their shape, improve their focusing power and halt the thinning process before vision is further impaired.

The Procedure

This outpatient procedure takes about 90 minutes if both eyes are being treated. Your doctor may prescribe a sedative or anti-anxiety pill to help you relax. You’ll lie on your back in a reclined chair and receive numbing drops in your eyes. Your ophthalmologist will remove the epithelium, the thin outermost layer of your cornea. She or he will insert riboflavin drops into your eye or eyes while you focus on a blue ultraviolet light. The combination of riboflavin and light strengthens your collagen crosslinks. The procedure is painless, but you may experience soreness afterwards.

The Epithelium Question

A less invasive CXL approach called transepithelial CXL is available for patients whose corneas are still thick enough to withstand this treatment option. This technique allows the epithelium to stay on, rather than be removed. A study by CXL-USA, a research group of eye doctors working on keratoconus and other corneal disorders, concluded that visual acuity was better in the transepithelial group. Results were about 20-percent better three and six months after CXL in the patients who retained their epitheliums. However, studies are still in the early stages.


All surgery has risks. With CXL, risks include infection, delayed epithelial healing, hazy vision and scarring. According to a 2012 article in the Journal of Ophthalmology, the doctors interviewed found these risk only affected a very small percentage of the total cases. Risks must also be weighed against the alternatives, which include progressive vision loss and the need for corneal transplantation, a much more invasive procedure.

Recovery and Results

Post-surgery, most patients may find their vision is worse than before. However, they notice improvements within two months. Some patients experience a major vision improvement three to six months after the procedure. Their vision may continue to improve for five years. Patients who have the transepithelial procedure, wherein their epithelium remains intact, generally report faster recovery and improvements to their vision.

If you suffer from keratoconus and want information about CXL clinical trials, call us today. We’ll help you determine the best options to maximize your vision.


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