Nonsurgical Solution Helps Correct Myopia

A new system uses accelerated photorefractive intrastromal cross-linking (PiXL) procedures for the treatment of myopia and keratoconus.

The KXL II System uses a combination of long ultraviolet (UVA) light waves and riboflavin (vitamin B2) to form cross-linked chemical bonds within the cornea, increasing its rigidity and stability. During the treatment, a photosensitive preparation of ribolflavin eye drops is applied to the cornea, which is then soaked for approximately 60 seconds. The ribolflavin is then dynamized by the UVA rays, a step that lasts for three minutes, during which the riboflavin penetrates the corneal surface by a few microns and induces the lamellae to move closer together.

The KXL II system achieves higher cross-linking speed by increasing UVA power and reducing the exposure time, thereby maintaining the same energy on the eye as standard cross-linking, while reducing cross-linking time by an order of magnitude. The outpatient procedure is noninvasive and painless, lasting for approximately, five minutes per eye from start to finish, compared to the 30 minutes time span required to carry out a standard cross-linking procedure. Another advantage is that it can be repeated later.

An further important advantage of the KXL II accelerated cross-linking system is that unlike the traditional technique, it does not involve removal of the corneal epithelium—the thinnest layer on the outside of the cornea—before administering riboflavin eye drops and UVA light. This allows thinner corneas to be cross-linked with greater precision, potentially decreasing risks and allowing patients outside current treatment criteria to be cross-linked. The KXL II System is a product of Avedro (Boston, MA, USA), and has received the European community CE marking of approval.

“The KXL II and PiXL procedure continue our mission to make refractive correction truly nonsurgical,” said David Muller, PhD, CEO of Avedro. “Treating myopia and other refractive disorders with PiXL has the potential to open up refractive correction to millions of people who have never considered Lasik surgery before, but would consider a nonsurgical alternative.”

“We experienced the amazing capabilities of customized accelerated cross-linking to achieve specific, reproducible, and interim-stable refractive changes on the cornea,” said A. John Kanellopoulos, MD, of the NYU Medical School (NY, USA). “It seems to me that every surgeon who has performed cross-linking has experienced refractive corneal changes. We now have a way to design and customize these refractive changes. If these initial clinical results continue to be repeated, as I believe they will, the potential seems unlimited.”

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