NOV 2013

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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38 EW FEATURE February 2011 Corneal crosslinking November 2013 Keratoconus patient selection for crosslinking by Erin L. Boyle EyeWorld Senior Staff Writer AT A GLANCE • A European congress on crosslinking established that keratoconus patients younger than 27 years of age should have crosslinking. • Older patients can benefit from crosslinking, especially those with progression or who are unable to wear contact lenses. • Contraindications differ for epi-on and epi-off procedures. • Patients should be adequately educated about what to expect from the treatment. Keratoconus patients who are candidates for crosslinking treatment range in age and progression, experts say P atients with keratoconus who show progression—or who are young and will most likely be facing advancement in the coming years—are excellent candidates for crosslinking, which has a high success rate of stopping progression, experts say. There is still no consensus on which keratoconus patients should be treated and when with crosslinking, so opinions can differ—just as they can differ over whether the epithelium should be removed or remain intact during treatment. The closest to a universal decision on appropriate patient selection was made at the 6th International Congress of Corneal Crosslinking in Milan in 2011, said Arthur B. Cummings, MB ChB, FCS(SA), MMed(Ophth), FRCS(Edin), medical director, Wellington Eye Clinic, Dublin. "It was decided that if you have keratoconus, if you're younger than 27, you don't need to have any evidence of progression, it makes sense to go ahead and crosslink," Dr. Cummings said. "The theory there is that if you have keratoconus [when you are] younger than 27, it is going to progress. You don't need any evidence that it has progressed." For cases older than 27 years of age, the general agreement is to look for signs of progression, he said. In his own practice, he also considers keratoconus patients as good candidates for crosslinking if patients report, and topography shows, worsening vision, or if they can no longer wear contact lenses. Patient selection William B. Trattler, MD, cornea specialist, Center for Excellence in Eye Care, Miami, said he disagrees with the practice in Europe of watching for progression in patients older than 27. In his experience, crosslinking has led to improvement in visual quality, regardless of patient age or stage of keratoconus, he said. Dr. Trattler, who uses epithelium-on crosslinking in the CXLUSA multicenter clinical trial in the U.S., said it is key to first identify patients with keratoconus, as many could be undiagnosed. After keratoconus has been established on topography, crosslinking can be a valuable tool to offer patients, he said. "Crosslinking is a potent and powerful technology … it does more than just stop progression. It actually results in improvement in corneal shape and improvement in vision in more than half of patients," said Dr. Trattler. "It's a therapeutic procedure that can result not only in the improvement of quality of vision, but also quantity of vision. For instance, some patients who weren't legal to drive in glasses prior to crosslinking can end up being able to drive afterward." He called crosslinking a "safe and effective therapy," which can help patients regardless of whether they have a history of progression. Doyle Stulting, MD, PhD, director, Stulting Research Center, Woolfson Eye Institute, and professor emeritus of ophthalmology, Emory University, Atlanta, said he believes crosslinking is indicated, in most patients, "as soon as keratoconus is diagnosed." He said crosslinking may have a benefit, even in older patients with a stable refraction and topography. "We have seen many patients with a significant improvement in vision and topography, even though they Pentacam difference maps from preop to postop day five—left eye above and right eye below. Difference map in the bottom right shows the flattening effect inferiorly (blue) and the steepening effect superiorly (black) that the SimLC has brought about on the left eye. Source: Arthur B. Cummings, MB ChB are older and do not seem to be progressing. Having performed this procedure for more than five years, I have become more comfortable with the risk profile and now believe it should be offered to virtually everyone with keratoconus, as soon as the diagnosis is made, unless the disease is extremely advanced with scarring and extreme thinning of the cornea," Dr. Stulting said. When asked who are the best keratoconus patient candidates for crosslinking, Theo Seiler, MD, PhD, Institute for Refractive and Ophthalmic Surgery, Switzerland, who invented the procedure in 1998, said the answer is easy. He still performs crosslinking with the epi-off procedure only. "It's the question, does the patient benefit from crosslinking? Since we can promise that the keratoconus stabilizes, it takes the patient benefit from the fact that we stabilize the current situation," said Dr. Seiler. "There are young people where we know that the keratoconus progresses and who benefit from crosslinking because they never come to a stage where they need additional surgery." He said in some advanced cases, when patients can still see well and tolerate contacts, crosslinking can assist those patients in wearing contact lenses for many years. First patients selected Patient selection for crosslinking has been a subject of interest. When Dr. Seiler developed crosslinking, he said he and his colleagues did not know which patients were the best candidates for the procedure. As with all new procedures, the typical trial methods were used to determine the safety of crosslinking— animal experiments, enucleated eyes, and finally, desperate cases that needed corneal transplants. "When we learned a little bit more, we looked for progressive keratoconus," Dr. Seiler said. "We learned that in principal, with irradiation sources we had at that time, we could stop progression. Today we have better light sources, and we know that in 60% of cases, we can make the keratoconus regress." He said that once the best indications were established, selecting the most appropriate patients for the procedure was simple. "We looked for adults with progressive keratoconus, and there were tons of patients available, and they were happy to get the treatment that works with a more than 90% chance of avoiding corneal transplants," he said. His first case in a human eye was in 1999 in Dresden, an 18-yearold male with hydrops in one eye, which had undergone an emergency transplant. "[His] parents asked me whether I could do something for his fellow eye—they didn't want to have the same story again—and then we did the crosslinking," Dr. Seiler said. "This eye still doesn't need corneal transplantation. This is now 14 years ago."

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