EyeWorld India March 2016 Issue

54 EWAP refractive March 2016 SMILE appearing The SMILE technique may also offer an alternative to the wavefront approach for some patients. This uses a femtosecond laser to create a lenticule in-situ, Dr. Yoo explained, adding that the lenticule is carefully dissected from the inner part of the cornea through a small incision. By removing this, physicians can get the desired refractive effect. This technique targets a group akin to wavefront, with similar myopic, myopic astigmatic, and hyperopic errors, she said. While not yet approved in the U.S., Dr. Yoo has been among the investigators of the approach. “Although we were just treating myopia in the clinical trials, the patients did very well,” she said. Investigators found patients reported a great deal of comfort after the surgery. “They didn’t have that 6–8 hours of severe photophobia, tearing, and foreign body sensation that some LASIK patients can have in the first few hours after surgery,” Dr. Yoo said, adding that in the postoperative visits, it seemed as though patients didn’t complain as much about dry eye symptoms, especially as they got further out from the surgery. Dr. Manche agreed that SMILE may be preferable for those prone to dry eyes. He pointed out that with SMILE, which preserves more corneal nerves with its smaller incision, there is a faster recovery of corneal sensation. “If we look at the studies that examined sub- basal nerve density after LASIK and PRK, in the early postoperative period, it is better with SMILE than it is with LASIK. While more testing is needed, for someone with borderline dry eye, the SMILE technique may be favorable for this reason,” he noted. SMILE also has a biomechanical advantage over LASIK, Dr. Manche pointed out. “You’re removing tissue from the posterior stroma and that contributes less to tensile strength than the anterior stroma,” he said. “From a biomechanical standpoint, the argument is it may be safer than LASIK.” Still, the SMILE technique is not for everyone, he said, pointing out there will be a percentage of patients who do not end up seeing 20/20 with this approach. “With those patients, you’re stuck,” Dr. Manche said. While with LASIK you can lift the flap and easily do a touchup, traditionally with the SMILE technique, PRK has been the retreatment approach, which may or may not be acceptable to patients. Dr. Manche expects SMILE to hit the U.S. market in 2017, with initial availability for treating spherical myopia. He thinks the technique is an important addition to the refractive armamentarium. Dr. Manche said that at Stanford, they have plans to do a prospective, randomized, head- to-head, clinical trial comparing SMILE surgery to LASIK, beginning in 3–6 months and also including two other major academic centers. EWAP Editors’ note: Dr. Manche has financial interests with Abbott Medical Optics (Abbott Park, Ill.). Dr. Yoo has financial interests with Alcon, Abbott Medical Optics, and Carl Zeiss Meditec (Jena, Germany). Contact information Manche: edward.manche@stanford.edu Yoo: SYoo@med.miami.edu Views from Asia-Pacific Hungwon TCHAH, MD Asan Medical Center, University of Ulsan 388-1 Pungnab-dong, Songpa-gu, Seoul, South Korea Fax no. +82-2-4706440 hwtchah@amc.seoul.kr On ‘Laser or inlay?’ and ‘Beyond pure wavefront’ T he advantages of corneal inlays are that they are additive and do not remove tissue, they preserve future options for presbyopia correction, and are removable. Currently, available corneal inlays are a successful treatment for presbyopia (as opposed to ametropia). Such inlays are usually implanted on the corneal stroma of the non-dominant eye, either under a corneal flap or within a corneal pocket. There are three types of corneal inlays available in the Asia-Pacific region: refractive inlays, which alter the refractive index using a bifocal optic; inlays that rely on the principle of pinhole optics; and hydrogel inlays that change the corneal curvature. Presbyopia-correcting corneal hydrogel inlays reshape the anterior curvature of the cornea and enhance both, near and intermediate vision using a multifocal effect. I would agree with Dr. Schalhorn’s choice of corneal inlay. However, after corneal inlays are inserted, patients need to understand that there is a slight reduction in contrast sensitivity at night. In my case, after insertion of a pinhole optic inlay, some patients have complained about deteriorated vision at night and at a distance. However, the pinhole optic inlay has shown better outcomes for near vision. Therefore, I choose patients for the inlay procedure based on their lifestyle. If the patient desires better intermediate vision with no decrease in distance vision, I recommend the hydrogel inlay. However, if he/she requires near vision, I recommend the pinhole optic inlay. There is minimal haziness around corneal inlays which usually does not prevent good vision but some need long-time steroid to suppress that. Topography-guided laser refractive surgery smoothens irregularities in the front corneal surface to achieve the desired refractive outcome. This technique is commonly applied in highly aberrated corneas where wavefront aberrometry is often not possible. In most cases, wavefront-guided treatments attempt to improve refractive outcomes by addressing higher-order aberrations of the optical system. As Dr. Manche pointed out, the SMILE technique seems to have less chance of inducing dry eye and to be safer in trauma than LASIK procedure. The result Editors’ note: Dr. Tchah declared no relevant financial interests. Beyond - from page 53