Eyeworld

EW CORNEA 45 CXL-USA preliminary study results The CXL-USA Study is a prospective, non-randomized, multicenter study evaluating both epi-on and epi-off crosslinking on up to 1,000 eyes with follow-up through 6 months. Patients could be enrolled in the study if they had keratoconus, forme fruste keratoconus, pellucid, post- LASIK ectasia, or RK with diurnal visual fluctuations. Additionally, pa- tients could be as young as 12, but the corneal thickness had to be at least 300 microns. Any thinner than 300 microns and patients "could run into potential damage because the corneas may not be thick enough to absorb the UV light," Dr. Luchs said. "The initial protocol was for 1,000 eyes. We're doing bilateral crosslinking, but we could do unilat- eral if necessary," Dr. Rubinfeld said. The protocol criteria began with epi- off as the technique, "but as we started to hear more about transep- ithelial procedures, we started to try to replicate the results the European studies had. Our study is an out- come study, not randomized, so the flexibility to alter the procedure of choice was available." Providing the patient meets all the study criteria, he/she will now generally undergo epi-on, Dr. Rubinfeld said. For those with corneas closer to the lower end of the corneal thickness inclusion pa- rameters of the study, they can sometimes be swelled to "at least 400 microns. In some, that still won't happen even with hypotonic eye drops. For those patients, we can offer the epi-off procedure [and] de- bride the epithelium, which will allow the cornea to swell more to safer thickness levels," Dr. Luchs said. Dr. Luchs presented preliminary results from one of the centers in- volved in the study; this particular center evaluated 36 patients who underwent the epi-on procedure and 20 who underwent the epi-off, he said. "Looking at the difference maps of the corneal topography is the key here," he said. "Difference maps show the improvement in corneal shape, and that's what correlates best with the improvements in vi- sual functioning and the BCVA [best corrected visual acuity] these pa- tients will experience." The im- provement in the overall shape of the cornea correlates best with the improvement in visual function. At 3 months, 52.6% of the epi- off eyes had improved BCVA, and 63.9% of those in the epi-on group had improved BCVA. By 6 months, 45% of those in the epi-off group had improved BCVA, and 62.5% of those in the epi-on group had im- proved BCVA. Dr. Luchs said people who had epi-off tend to see signifi- cantly worse at first, "which may be due to the scraping of the epithe- lium," he said. After the epithelium has been debrided and begins to grow back on, "it does so in a uni- form thickness across the cone. So it will mimic the underlying corneal curvature without the masking ef- fect of epithelial thinning over the cone." He believes in the long term both sets of patients will be able to see better, but those in the epi-on group will do so quicker and less painfully. Initially it was thought keratoconus naturally stops pro- gressing some time in the late fourth decade of life and therefore, crosslinking would be ineffective or unnecessary. What the CXL-USA Study Group found, however, was that older patients are experiencing "an improvement in the quality of their vision, despite their age," Dr. Luchs said. Additionally, the crosslinking procedure is "reason- ably noninvasive, and they don't lose the potential to pursue other options if required, such as Intacs [Addition Technology, Sunnyvale, Calif.] and corneal transplants." Dr. Rubinfeld noted a "substan- tial number of patients have now ex- ited the study," since follow-up was designated to be 6 months. "There has not been a case of progression or regression," he said. "What we're finding is the earlier a patient is treated, the more likely we are to stop progression of these dis- eases. There doesn't seem to be any benefit in waiting until the disease is severe to treat the patient. In Eu- rope, patients are being treated as young as 9. If you compare the safety and efficacy of corneal trans- plant to early crosslinking, crosslink- ing wins. Preventing these diseases (as in most of medicine) is better than treating them." EW Editors' note: Drs. Luchs and Rubinfeld are investigators in the CXL-USA Study. Dr. Rubinfeld also holds patents on the device used in the study. Contact information Luchs: 516-785-3900, jluchs@aol.com Rubinfeld: 301-654-5114, rubinkr1@aol.com October 2011 Visit us at AAO Booth 2978 40-45 Cornea_EW October 2011-dl2_Layout 1 9/29/11 3:43 PM Page 45

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