Eyeworld Supplements

EW MAY 2016 - Daily 1 - Supported by Alcon a Novartis Company

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T opography-guided ablations have been an integral part of my practice for a dozen years. My primary practice is based in Athens, and topography- guided ablations are time-tested and common outside the U.S. Now, with the FDA's approval of topography-guided custom ablation treatment (T-CAT) for eyes with myopia and myopic astigmatism, topography-guided LASIK ablations are an option here in the U.S. 1 A new paradigm The FDA study of topographic-guided refractions in virgin eyes establishes a new paradigm of even better outcomes. An intrinsic advantage of topogra- phy-guided ablations became evident as a result of the phase 3 clinical study that was the basis for T-CAT approval: A large percentage of eyes gained lines of vision. 1 This is probably associated with the subtle cornea irregularities that even normal eyes have. These irregularities are addressed by topography- guided ablations, which by definition normalize any cornea to maximum symmetry and apply the correc- tion on the cornea apex (taking into account angle kappa). This appears to enhance visual function. The differences between wavefront-guided methods and topography-guided methods are quite simple; wavefront-guided removes a lot of tissue to make a cornea more spherical based on the flattest part of the cornea. Topography-guided methods "shave" off the peaks of cornea curvature and aim to steepen flatter areas by ablating around them and indirectly steepening those flatter areas. This bimodal approach of simultaneous hyperopic and myopic treatment provides an advantage, in my opinion, because it removes much less tissue. In some instances, one-third less tissue is removed with topographic-guided ablations than with wavefront-guided ablations. I find topography-guided methodology much easier to understand than wavefront-guided methodology. Wavefront is an approach dependent on theory that I cannot necessarily grasp by looking at objective topography data. Beneficial for routine cases Even as a seasoned topography-guided surgeon, I have learned a great deal from the FDA study data that further supports my reliance on topography- guided methodology. The findings show that T-CAT is beneficial for virgin eyes, and this has led me to use it in my routine LASIK cases. I see a significant ad- vantage in the fact that in "normal" corneas T-CAT can further normalize the cornea and offer better vi- sual acuity and more lines of gained vision (Figure 1). For this as well as the reasons stated earlier, I consider topography-guided treatment to have ad- vantages over wavefront-guided treatment. Figure 1: These scans illustrate a –6 D female who underwent routine femtosecond laser LASIK with the Alcon Refractive Suite. The right eye was treated with T-CAT, and the left eye with wavefront-optimized. The IHD values improved in the right and deteriorated slightly in the left, perhaps explaining the improvement in UCVA in the right from CF (CDVA 20/20) to 20/10 and in the left from CF (CDVA 20/20) to 20/20. Two lines were gained in the OD and no lines gained in the OS; these corneas would be classified as normal, but the slightly steeper superior half benefited from the T-CAT normalization, and this improved the visual outcome. Why I believe in topography- guided ablations by John Kanellopoulos, MD Michael Gordon, MD Ophthalmic surgeon, Gordon Schanzlin New Vision Institute, San Diego 2 For important product information about the WaveLight Excimer Laser System, please see page 6. " Contoura TM Vision offers such great results, it should be offered to every eligible patient. " Reference 1. Topography-guided Custom Ablation Treatment or T-CAT Summary of Safety and Effectiveness Data (SSED), available at: www.fda.gov/MedicalDevices/ProductsandMedical- Procedures/DeviceApprovalsandClearances/ Recently-ApprovedDevices/ucm372964.htm.

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