UV collagen cross-linking shows encouraging results in French study

PARIS — UV corneal collagen cross-linking is showing encouraging results in patients with keratoconus and post-LASIK ectasia, according to the results of a study conducted at two centers in France.

David Touboul, MD, and Pierre R. Fournié, MD, respectively under the direction of Joseph Colin, MD, in Bordeaux, and François Malecaze, MD, in Toulouse, discussed favorable experimental results with cross-linking, which they think could change the outcomes for many keratoconus patients.

"To date, there is no device that can measure the changes in corneal stiffness in vivo, but laboratory ex vivo studies have largely demonstrated that the treatment indeed produces a cross-linking of collagen fibers that leads to increased corneal rigidity and re-structuring," Dr. Fournié said here at the French Society of Ophthalmology meeting.

What is seen clinically is a halting of keratoconus progression in most patients, he said.

"Results are not uniform," Dr. Touboul said. "The individual response to the treatment is quite variable, for reasons that are still unknown; however, in most patients, keratoconus progression is halted or at least slowed down, and visual acuity increases quite a few lines."

Both physicians pointed out that it is still early to draw definitive conclusions, and although UV cross-linking so far has been shown to cause no complications apart from transient haze in some cases, they recommended caution. The treatment should be administered only in cases of proven keratoconus progression, and patients with corneal thickness that is 400 µm or less should not be candidates for the procedure because riboflavin, and consequently UV light penetration, in these thin corneas would cause severe damage to the epithelium.

"Hopefully, we will be able to produce new molecules that will allow us to safely use the procedure also in thinner corneas," Dr. Touboul said.

No limitations seem to be necessary in terms of age, but early stages of keratoconus appear to respond better, he said.

While the IROC system was initially used in both centers, Dr. Touboul said that best results were obtained with the new CBM X Linker, which may be more user-friendly and more precise.

Accurate antiseptic measures were recommended, as well as the application of a therapeutic contact lens and the use of topical antibiotic and corticosteroid therapy after the treatment.

"In spite of the cornea being disepithelialized and remaining exposed for 1 whole hour, we had no case of infection," Dr. Touboul said.