EyeWorld Asia-Pacific September 2015 Issue

39 EWAP REFRACTIVE September 2015 on the cornea as opposed to the WaveScan, which was about 250,” he said. Dr. Coleman thinks this new technology offers better outcomes and decreased enhancement rates. “My feeling has always been that the single most important number in a practice is the enhancement rate,” he said. “It’s incumbent on the surgeon to keep that number very low for a variety of reasons.” When he took part in the FDA trial for the iDesign, he had excellent results. “I have a zero enhancement rate for my cohort of patients and my outcomes were tremendous,” he said. The quality of vision in the iDesign study was also outstanding, he said. Patient questionnaires showed decreased halos and glare. “My general sense is that the quality of vision is improved with the iDesign because there are more data points and the way that the treatment profile is laid down on the cornea is more customized, more accurate,” he said. Another unique approach now in use is topography-guided LASIK. Arthur B. Cummings, MD , Wellington Eye Clinic, Dublin, Ireland, explained that the technique can be applied to regularize the cornea while correcting the refractive error. “Consider doing a wavefront- guided procedure with an eye that has wavefront errors despite having a perfect cornea. After the procedure, the cornea will be irregular to compensate for the intraocular irregularities. With topography-guided, that’s not the case—the cornea is always made more regular,” Dr. Cummings said. This offers the potential to get better results with customized, primary treatments. In addition, the topography maps are repeatable. “You can take 10 topography maps and the 10 will almost look identical,” he said. The topography-guided approach adds significant value to retreatment, he said. For patients who have a decentered ablation or a small optical zone, this approach works best, he stressed. With wavefront corrections, the only option practitioners have is to strive for emmetropia and attempt to remove all aberrations, Dr. Cummings explained. The topography-guided approach, however, offers flexibility in regularizing the cornea. “With topography-guided ablations, physicians have the ability to make the optical zone size any size in 0.1 mm increments,” he explained, adding that it is not necessary to use quarter diopter increments as it is with wavefront-optimized; with topography-guided, the refraction can be entered in 1/100ths. With topography-guided procedures, the final asphericity can also be controlled by adjusting the Q-value target. Dr. Cummings described the results from the topography-guided trial in the U.S. that led to the FDA approval of the WaveLight Allegretto Wave Eye-Q (Alcon, Fort Worth, Texas). These indicated that at 3 months, 93% of eyes were 20/20 or better, 69% were 20/16 or better, and 32% were 20/12.5 or better. These results highlight the power of regularizing the cornea during laser refractive surgery. From a clinical perspective, he thinks that primary topography- guided LASIK with its very good outcomes has the potential to get patient referrals going again. “LASIK has taken a bit of a beating in the last few years,” he said. “Now we might suddenly find that’s changed with better outcomes.” Also, Dr. Cummings said the approach can be used to repair results of LASIK cases gone awry. “When people start seeing the value of topo-guided as a repair tool, it will take the worry away from patients who currently aren’t having LASIK done for fear of some sight-damaging complications,” he said. Going forward, Dr. Cummings thinks there is one more important technology in the wings—ray tracing. This does what topography-guided LASIK can do but also includes refractive modeling of the eye, he explained. All of the other technologies irrespective of their diagnostics apply the data to a generic eye (Gullstrand model). Ray tracing uses a virtual model of the patient’s own eye as represented by data points from devices providing corneal, wavefront, biometric, and refractive data, he said, adding that the results will likely be even more accurate. But the advent of this is still a couple of years away. EWAP Editors’ note: Dr. Cummings has financial interests with Alcon. Dr. McDonnell has financial interests with Allergan (Dublin, Ireland) and GrayBug (Baltimore). Dr. Coleman has no financial interests related to this article. Contact information Coleman : Stephen@colemanvision.com Cummings : abc@wellingtoneyeclinic.com McDonnell : Pmcdonn1@jhmi.edu Index to Advertisers Appasamy Associates Page: 43 www.appasamy.com Haag-Streit Page: 15 www.haag-streit.com Lacrimedics Page: 35 www.lacrimedics.com Moria Page: 27 www.moria-surgical.com OCULUS Optikgeräte Page: 21 www.oculus.de Rayner Intraocular Lenses Page: 31 www.rayner.com Shanghai Mediworks Page : 2 www.mediworks.com.cn Topcon Corporation Page : 9 www.topcon.co.jp Ziemer Page: 68 www.ziemergroup.com ASCRS Page: 54 , 64 , 67 www.ascrs.org APACRS Page : 5, 48 www.apacrs.org