EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/618732
35 EW FEATURE better for normal eyes," he said. "If you have a normal eye, there's really no reason to do a topographic LASIK treatment." Dr. Lin only performs topo- guided treatments for decentered ablations, optical zone enlarge- ments, patients with keratoconus or patients post-keratoplasty or radial keratotomy (RK). For most of these patients, however, he chooses to do PRK rather than LASIK. "My phi- losophy is that if the eye is already asymmetrical and aberrated from weakening, in this case, they should not have LASIK because LASIK weak- ens the eye even more." Although both topo-guided LASIK and PRK are available interna- tionally, only topo-guided LASIK is FDA-approved at this time. Another thing to keep in mind is that flap creation is slightly different for topo-guided ablations. "Topography-guided treatments will be centered on the visual axis, so they will take into account angle kappa by definition. Thus if the patient has significant angle kappa, flap-making has to adjust to that as well," Dr. Kanellopoulos said. "Usually a patient's angle kappa has a corneal apex that is skewed nasally and slightly inferiorly, so the same has to be done with the flap design and creation." When to move on to irregular corneas Drs. Solomon and Lin advised caution when deciding to move on to treating irregular corneas. Only when surgeons start getting good, consistent outcomes on normal eyes and the surgical process is stream- lined should they start tackling irregular or previously treated eyes, Dr. Solomon said. "In Europe and around the world, this technology has been extremely helpful for patients who have had previous refractive surgery, expanding the optical zone, treating irregular astigmatism, corneal irreg- ularities, and decentered ablations," Dr. Solomon said. "There's certainly a lot of excitement about using to- po-guided treatments to treat those eyes, but there's a lot that we still have to learn about that. It's not so cut and dry." Dr. Lin has been performing topo-guided treatments for 15 years, but the majority of that time has been spent developing and perfect- ing an algorithm for calculating the correct treatment plan for each patient. The goal of topo-guided ablations is to normalize the corneal surface, but in irregular corneas, neutralizing all sphere and cylinder can actually induce an unplanned refractive error, he said. As an ex- ample, Dr. Lin found that setting a target of plano on a +4 D post-RK patient induced an 8 D myopic shift. "Once you get into aberrated eyes, you cannot use a refraction without compensation," Dr. Lin said. "It's very dependent on the preoperative state of the eye. We figured out an algorithm to [correct] this, but it took us 5–10 years. For the average surgeon, they will have to be very careful to select the right patients." The bottom line is that it takes years to become comfortable with treating highly aberrated corneas, Dr. Lin said. He thinks that surgeons should be comfortable after treat- ing roughly 100 aberrated eyes, but these eyes are rare in a practice. "The minute you include aberrations, the algorithm becomes very complex," he said. "So it takes dedicated surgeons to take courses on how to neutralize these corneas and then treat the refraction." Despite these challenges, the physicians have been happy with the visual outcomes they have achieved with the technology. "The results have been spectacular," Dr. Solomon said. "I'm excited and thrilled to be able to offer this to patients." Surgeons should contact their Alcon sales representative to learn more about getting started with the Contoura system. EW Editors' note: Dr. Lin has financial interests with PRN (Plymouth Meeting, Pa.) and Schwind Eye Tech Solutions (Germany). Dr. Solomon has financial interests with Alcon. Dr. Kanellopoulos has no financial interests related to this article. Contact information Kanellopoulos: ajkmd@mac.com Lin: tclin@shaw.ca Solomon: kerry.solomon@carolinaeyecare.com A F R E S H P E R S P E C T I V E ™ © 2015 Lacrivera, a division of Stephens Instruments. All rights reserved. 2500 Sandersville Rd ■ Lexington KY 40511 USA lacrivera.com ( 855 ) 857-0518 William J. Faulkner, M.D. Cincinnati Eye Institute The VeraPlug ™ challenge results are in. Try the VeraPlug. ™ What will you say? "The VeraPlug ™ has become my punctal plug of choice. Design features allow easy sizing, quick insertion and longer stability. Both patient and doctor are pleased."