After much anticipation and a long wait for both clinicians and patients in need, the U.S. Food and Drug Administration (FDA) approved corneal cross-linking (CXL) in mid April. This procedure is globally considered the only method of halting the progressive family of diseases called corneal ectasias, including keratoconus. Specifically, the FDA approved two formulations of riboflavin solutions, Avedro’s Photrexa Viscous and Photrexa, and a UV-A light source, the KXL System for Corneal Cross-Linking.
This procedure will now be readily available for the thousands who suffer from diseases such as progressive keratoconus. However, it is still in a very early phase post-approval. There is a limited amount of devices on the market, and an insurance code is not yet available.
How CXL originated
CXL is a procedure credited to Professor Theo Seiler, MD, an ophthalmologist and mathematician who, when teaching at the University of Dresden in the mid 1990s, came up with the idea while visiting a dentist. As the story is told, the dentist was utilizing crosslinking on Seiler during a dental procedure when the idea came to Seiler to apply this strengthening procedure to the weakened keratoconic cornea.
Think about the last time you brought your child in for a dental filling. The last component of the treatment is to strengthen the filling material with a UV light. That is a form of crosslinking. Ever get a gel manicure? The last step of the procedure is to place the gel polish on your nails under the UV light source to harden the polish. Again, this is a form of crosslinking.
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Crosslinking is nothing new, it’s just new to us in the U.S. Dr. Seiler saw the potential opportunity and patient benefits and assembled his team with Gregor Wollensak, MD, and Eberhardt Spöerl, MD. The animal research began on corneas, and the rest is history.1
According to Roy Rubinfeld, MD, inventor of the CXL-USA CXL device, “By September 2006, all 25 European Union (EU) countries had approved CXL, and it was obvious that it worked. U.S. corneal specialists found it frustrating that they did not have access to the technology, and these physicians felt badly that patients with keratoconus were continuing to lose their vision. Some of us got together and formed our own group and set up a physician-sponsored, Institutional Review Board-approved series of protocols under the auspices of the CXL-USA Study Group.”1
Related: When do you diagnose keratoconus?
Fast forward to 2016—a decade later—and an FDA approval. The global community firmly established and proven through hundreds of peer-reviewed studies and meta analyses3,4 the safety and efficacy of this procedure for treatment of the family of corneal ectatic diseases.5 It has shown its effectiveness in treating infectious keratitis (mycobacterium and Acanthamoeba) that are not commonly susceptible to commercially available antibiotics.6
The question is not, “Where are we with CXL in the U.S.?” because we are clearly lagging behind but rather, “Where is CXL globally?” and “What else can we do with CXL?”
To the keratoconic patient, poor quality of vision and fear of a potential corneal transplant are the biggest problems with his disease. What if you could not only halt the disease but also improve refractive error? The answer for the patient is in the reduction of refractive error in conjunction with CXL. As we know, due to the steepening of the cornea in an ectatic patient, the type of refractive error is likely myopia and astigmatism. Ophthalmologists, optometrists, and researchers around the world are vigorously seeking to solve this all-too-common problem. Currently, there are various methods in which to achieve the stability and refractive goals simultaneously.