EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/176967
February 2011 September 2013 Crosslinking was completed several years ago, it took some time to complete the data analysis and move on to the submission stage. Dr. Hersh indicated that the study is proceeding at an expected pace. Dr. Muller said that Avedro is the only company so far in the U.S. that has a trial that is expected to produce some sort of approval for crosslinking. He said Avedro expects to submit the data from its clinical trial to the FDA sometime in September. "With a little luck, we hope that approval will be within six months of that submission," he said. Though this approval could come as early as the first quarter of next year, Dr. Muller noted that it would just be for the first generation protocol of crosslinking, based on data from some years ago. Current crosslinking being done around the world and trials starting now in the U.S. are much more advanced than that, he said. Newer protocols include shorter procedure time with more effective parameters. Dr. Hersh said Avedro has completed another clinical trial of accelerated crosslinking, which is currently conducting follow-up with patients. In addition to Avedro's work, he indicated that there is a multicenter study with transepithelial crosslinking being conducted by CXLUSA. Dr. Rubinfeld is currently working with CXLUSA, which he started because the rest of the world seemed to have access to a treatment for keratoconus that was not available in the U.S. "With a group of excellent physicians and a lot of regulatory advice from professionals and some significant personal funds, I started a physician-sponsored, IRB-approved, clinical study in the U.S., and we called it CXLUSA," he said. Dr. Rubinfeld said CXLUSA has grown from a single site to now more than a dozen with about 38 investigators across the U.S. "We have over many years, with several protocols, been treating quite a number of patients with superb results," he said. IRB studies are convenient for being able to modify and amend protocols based on rapid analysis of data, Dr. Rubinfeld said. Other forms of crosslinking and possible combination therapies Dr. Hersh said his center is involved in a multicenter clinical trial with crosslinking being used as an adjunct to LASIK. Earlier this year, Dr. Hersh visited Colombia to examine the technique for performing crosslinking as an adjunct to LASIK. "The clinical trial will be starting in the U.S. looking at hyperopic LASIK using adjunctive crosslinking," he said. Patients with between 2.0 D and 6.0 D of hyperopia will be eligible. Dr. Hersh said there have been other studies to look at crosslinking with a combination of procedures. "We have been undertaking a trial looking at combination therapies, in particular crosslinking with Intacs," he said. With crosslinking, the main goal is to strengthen the weak cornea and prevent progression, while Intacs aims to flatten the cone and make the cornea more symmetric. Since the two procedures have different clinical objectives, it would seem that these therapies would work well together. Dr. Hersh said there were two goals of this experiment: to look at safety and efficacy using these procedures adjunctively and to see if the timing for the procedures was important. He said it had to be determined clinically whether it was better to do the two concurrently or if they should be spaced. Although the study is still ongoing, early analysis suggested that the use of these two treatments is effective, and there does not seem to be a major difference between concurrent and sequential surgery, Dr. Hersh said. "I think crosslinking and Intacs is a great solution," Dr. Donnenfeld said. The crosslinking will help prevent progression of the disease, while Intacs helps to improve vision. In addition to crosslinking with LASIK and crosslinking with Intacs, worldwide there have been experiments with the combination of crosslinking and topography-guided PRK. Although this is not available in the U.S., there have been encouraging results elsewhere, Dr. Hersh said. "I think that crosslinking as an adjunctive procedure to a number of [procedures] is something that we're going to be seeing more and more of," he said. Dr. Rubinfeld discussed a combination therapy with crosslinking that CXLUSA developed a protocol for about 15 months ago. "We have been combining conductive keratoplasty [CK, Refractec, Bloomington, Minn.] with crosslinking," he said. Both are epi-on procedures and both are relatively non-invasive. "We have found incredibly rapid visual recovery and marked improvement in the regularity of the corneas." So far, results are stable and there are impressive data over a 12month period. "One of the problems with CK in the past is that the results didn't necessarily last as long," he said. However, by combining the treatment with crosslinking, this has helped to "lock in" the effect of CK, and Dr. Rubinfeld said it "has been astonishingly effective in quite a number of eyes." The future of crosslinking Dr. Hersh said he believes that international clinical trials and U.S. multicenter clinical trials show good evidence that it's a "safe and effective procedure." He said that moving forward, some of the important issues to examine are efficacy of transepithelial crosslinking, the safety and efficacy of accelerated crosslinking with higher power, and the use of accelerated crosslinking as an adjunct to LASIK. "We know crosslinking works," Dr. Rubinfeld said. There have been dozens of well-performed studies, he said. "I can't express in words how gratifying it is to stop patients from losing their vision to irregular astigmatism in keratoconus and post-LASIK ectasia." Dr. Rubinfeld said he is pleased with the data from EW SECONDARY FEATURE 57 CXLUSA, which demonstrates good efficacy and reduced risk with the epi-on procedure as compared with making a large epithelial defect in the epi-off procedure. "There's no question that corneal strengthening is one of the major advances in the last several years and will be one of the key advances in ophthalmology for at least a decade as we move toward refractive indications and other indications," he said. Dr. Donnenfeld said his hope is that keratoconus becomes a disease similar to polio in that it ceases to exist because there is a therapy that can stop the disease. "The morbidity and quality of life associated with keratoconus mandates that we as compassionate ophthalmologists implement this treatment, which can change literally thousands of lives on an annual basis," he said. "Ophthalmology in the U.S. is certainly ready for crosslinking to be approved, and I believe we have the data to support that," Dr. Muller said. "Hopefully the FDA will agree with us." EW Editors' note: Dr. Hersh has financial interests with Avedro. Dr. Rubinfeld has financial interests with CXLUSA and CXLO. Dr. Donnenfeld has no financial interests related to this article. Dr. Muller has financial interests with Avedro. Contact information Donnenfeld: ericdonnenfeld@gmail.com Hersh: phersh@vision-institute.com Muller: david@avedro.com Rubinfeld: rubinkr1@aol.com Watch this video on your smartphone or tablet using your QR code reader. (Scanner available for free at your app store.) In this video, Avedro describes Lasik Xtra, corneal crosslinking during a LASIK procedure to preserve corneal biomechanical integrity. Source: Avedro