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New microwave procedure promising for treatment of keratoconus, related refractive error
The procedure uses microwave energy to flatten the cornea and cross-linking of UV and riboflavin to halt disease progression.
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 John Marshall |
A new microwave procedure, Keraflex KXL from Avedro, holds the promise of treating keratoconus while also correcting the associated refractive error.
“The Keraflex procedure flattens the cone and strengthens the cornea by changing the tension of collagen fibers. At the same time, it offers the possibility of correcting the refractive error that the steepening has produced, significantly improving vision. For the first time, we have a refractive procedure that results in strengthening of the cornea,” John Marshall, PhD, FMedSci, FRCPath, emeritus professor of ophthalmology at King’s College, London, said in a telephone interview with Ocular Surgery News.
The procedure is carried out in two steps. In the first step, microwave energy is applied to a ring-shaped area of the cornea using an annular electrode. The energy penetrates the superficial stroma, inducing localized shrinkage of the collagen fibers.
“Microwaves raise the temperature of the targeted region of corneal stroma and tighten up the collagen lamellae. By tightening an annulus of collagen, a central flattening is induced,” Dr. Marshall explained.
The annulus is placed in relation to the cone, so that a specific area is selected for flattening.
Step two entails a riboflavin-UV cross-linking procedure specifically within the microwaved area. The center and periphery of the cornea are masked using UV-blocking corneal shields. Riboflavin 0.1% is applied to the annulus following removal of the epithelium, and UV irradiation is carried out for 30 minutes.
“UV cross-linking is used to improve the stability and extend the lifetime of the flattening that Keraflex induces. The two procedures work synergistically,” Dr. Marshall said.
There are significant advantages in this combination compared to cross-linking alone, he noted.
“With conventional cross-linking, you freeze the cone, however bad, but hopefully halting disease progression. With Keraflex KXL, you first achieve some degree of refractive error improvement, and then freeze it,” he said.
Dr. Marshall was involved in the scientific development of the technique and in the treatments carried out in the first group of patients at Beyoglu Eye Research and Training Hospital in Istanbul, Turkey.
“Results were exceptional, beyond the wildest dream,” he said. “All the patients we treated had significant cones and they all flattened to a more prolate cornea, with remarkable improvement of vision.”
Currently, the Vedera KXS system for performing the Keraflex KXL procedure is undergoing European clinical trials and is not yet available commercially. – by Michela Cimberle
- John Marshall, PhD, FMedSci, FRCPath, can be reached at the Institute of Ophthalmology, Bath Street, London EC1V 9EL, UK; +44-20-7608-6950.