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Speaker: FDA approval of KXL System ‘a major advancement’
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NEW ORLEANS — The FDA approval of the KXL System for corneal collagen cross-linking is a major advancement in the treatment of progressive keratoconus, according to a speaker here.
“We as corneal specialists and our patients can look forward to use of corneal collagen cross-linking, which certainly is a major advancement in treatment of keratoconus,” Peter S. Hersh, MD, said during Cornea Day preceding the American Society of Cataract and Refractive Surgery meeting.
Peter S. Hersh
The FDA granted approval to the KXL System (Avedro) for corneal collagen cross-linking with Photrexa Viscous (riboflavin 5'-phosphate 0.146%/20% dextran ophthalmic solution) and Photrexa (riboflavin 5'-phosphate 0.146%) on April 16, 2016.
“Photrexa Viscous is used for corneal loading of riboflavin before the CXL procedure, and Photrexa is used for corneal swelling after the loading phase in corneas that are under 400 µm in thickness,” Hersh said.
The KXL System is an ultraviolet light-sourced platform operating at 365 nm UVA at a power of 3.0 mW/cm2.
“The procedure [that was] investigated which led to FDA approval was the traditional epithelium-off procedure with a 9 mm removal of the epithelium and corneal loading for 30 minutes using Photrexa Viscous solution every 2 minutes. We then checked at the slit lamp for adequate riboflavin uptake. We looked for complete uptake within the corneal stroma, as well as flare in the anterior chamber,” Hersh said.
For corneas less than 400 µm in thickness, the Photrexa solution is used every 10 seconds for 2 minute cycles until the cornea swells to over 400 µm, Hersh said.
The approval was based on results of two randomized controlled clinical trials, which included patients 14 years of age or older who were diagnosed with progressive keratoconus over 2 years.
“As you know corneal collagen cross-linking’s main goal is to diminish or stop the progression of progressive keratoconus. Maximum keratometry was chosen as an outcome that we could look at quantitatively to compare treatment vs. the sham,” Hersh said.
Researchers found stability and generalized improvement in corneal topography in the treatment group. The treatment group had a 1.6 D improvement in mean maximum keratometry (P < .01).
“Clinically, as you get into collagen cross-linking, you’ll notice that this is an outcome that improves over time. Patients tend to worsen in the very early periods and improve 3, 6 and 12 months afterwards,” Hersh said.
In 512 eyes that underwent CXL, CXL-associated stromal haze was the most common reported adverse event.
“This was the generalized haze that we typically see in the stroma as an expected concomitant of the cross-linking procedure, which typically evolves into a demarcation line over time and tends to be transient over the 1 year period,” he said.
Hersh advises surgeons to monitor patients for potential corneal ulcers as they would like any surface corneal procedure. – by Nhu Te
Reference:
Hersh P. U.S. cross-linking approval. Presented at: ASCRS; May 6-10, 2016; New Orleans, Louisiana.
Disclosure: Hersh reports he is the medical monitor for the U.S. multicenter clinical trials for Avedro.