June 14, 2016
4 min read

FDA approves corneal cross-linking for keratoconus

Optometrists say now the focus should turn to earlier diagnosis of the disease.

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The long-awaited FDA approval of Avedro’s corneal cross-linking system “opens the door for the evolution of this technology in the U.S.,” Scott G. Hauswirth, OD, FAAO, said.

In mid-April, the FDA approved Avedro’s cross-linking system for progressive keratoconus. The approval was unique, as it is a combination drug and device approval, the Photrexa formulations combined with the KXL device.

Avedro sought both FDA drug and device approvals, according to David Iannetta, Avedro’s vice president, marketing, in an interview with PCON sister publication, Ocular Surgery News.

Aligning the laser crosshairs of the KXL cross-linking system (Avedro) on a patient’s eye prior to initiating CXL treatment.

Image: Chang C

While some optometrists have been offering cross-linking to patients since April 2008, when the FDA studies commenced, “we can now present it with confidence that it is a proven treatment methodology and has the stamp of the FDA behind it,” Hauswirth, a Primary Care Optometry News Editorial Board member, said in an interview with PCON.

“Those of us who have been able to embrace this technology relatively early on in the U.S. have been wondering what took so long to receive approval here, because safety and efficacy studies have been published since 2003, and all of the E.U. has been able to offer it as an approved technology since 2006,” he added.

Avedro’s chief medical officer, Rajesh K. Rajpal, MD, said in an interview with OSN, “Optometrists and ophthalmologists who work together will determine how they continue to share in the care of these keratoconus patients. Certainly, patients after cross-linking continue to need optometric care. Many of them continue to wear contact lenses and are fit by optometrists in customized lenses frequently.”

Hauswirth explained that there are still many areas of the country where patients need to travel for this procedure, so the FDA approval will help infiltrate into some of those regions.

Clark Chang, OD, MS, FAAO
Clark Chang

“The ability to stabilize keratoconus and ectasia is something we’ve never had prior to the advent of corneal cross-linking,” Clark Chang, OD, MS, FAAO, explained. “Across all tiers of eye care, we never emphasized early diagnostic timing, because regardless of what stage you detect your patient, whether it’s mild, moderate or severe, nothing we did could stop or slow down the natural course of keratoconus. Therefore, we managed debilitating visual symptoms with glasses or contact lenses until a patient may require a corneal transplant.”

How the procedure is performed

Hauswirth highlighted that this epi-off corneal cross-linking (CXL) works by first infusing and saturating the corneal stroma with riboflavin and irradiating the cornea with a specific wavelength (360 nm) of light. The ultraviolet light creates free radicals, which then cause covalent bonding between adjacent stromal collagen fibers, which increases the tensile strength of the cornea and can halt ectatic disease.

Scott G. Hauswirth, OD, FAAO
Scott G. Hauswirth

One year after CXL treatment in clinical trials, an average of 1.7 D of flattening in the corneal apex region was achieved in the study population, according to Chang, who has worked with CXL since the first multicenter cross-linking study in the U.S. in 2008. He said the procedure may need to be repeated for some individuals when further progression can be documented, but the majority of patients followed for 10 years have remained stable, according to Raiskup and colleagues.

The future for CXL

Now that the momentum of disease can be stopped with CXL, Chang said, the clinical emphasis needs to change to how early patients can be diagnosed in order to maximally preserve visual function and visual quality in every patient. He wants to see the optometric community develop a shift in management principles to enable a diagnosis as early as possible.


“The FDA approval of corneal cross-linking will change our diagnostic and management approaches, not just in the development of new diagnostic instrumentation to better facilitate disease understanding and earlier detection, but also in how we will approach our eventual treatment recommendations,” he added.

Both Hauswirth and Chang believe optometrists could perform CXL in practice.

“This is the elephant in the room,” Hauswirth stated. “Technically, there does not seem to be a real scope of practice barrier to incorporating this procedure. However, depending on the cost of the equipment and insurance reimbursement, it may not be financially feasible for many ODs around the country to incorporate this into their practice.”

Chang reported that many optometrists he has spoken with appear to be more comfortable with the concept of epi-on CXL (yet to be FDA approved), which does not débride the epithelium prior to treatment.

He suggested a potential comanagement approach based on this. At detection of ectatic disease by the primary care optometrist, the epi-on procedure could be performed by the OD. Then, if in the future the disease progresses, the patient could be referred to a center for the epi-off procedure.

Chang and Hauswirth noted that other CXL protocols are being developed. Researchers are evaluating shortening the time of treatment from 20 to 30 minutes to only 3 or 4 minutes, and also looking beyond just epi-on and epi-off delivery methods.

“I have been able to see and manage these patients for over 8 years to this point and would not hesitate to have this procedure done on myself or my children should they develop keratoconus,” Hauswirth concluded. – by Abigail Sutton

Disclosures: Chang and Hauswirth report no relevant financial disclosures.