EyeWorld Asia-Pacific December 2014 Issue

40 EWAP REFRACTIVE December 2014 SMILE procedure (sphere only) Source: Vance Thompson, MD by Ellen Stodola EyeWorld Staff Writer SMILE uses femtosecond laser for corneal refractive procedure This new technique offers the option of doing an intrastromal procedure without a flap T he SMILE technique is a new method used with the VisuMax 500 kHZ femtosecond laser (Carl Zeiss Meditec, Jena, Germany) that provides lenticule extraction without creating a LASIK flap. John Doane, MD , Discover Vision Centers, Kansas City, Kan., U.S., and Vance Thompson, MD , Vance Thompson Vision, Sioux Falls, SD, U.S., discussed the procedure, the FDA-monitored trial, and some advantages and disadvantages. What is the SMILE procedure? The acronym SMILE stands for small incision lenticule extraction. “Instead of creating a flap, we make a lenticule of tissue within the stroma with an anterior and posterior pass of the femtosecond laser to create a three-dimensional piece of tissue that is manually removed through a 2–3 mm or 60 degree incision at the 7.5 mm optical zone,” Dr. Doane said. “The SMILE technique is a ‘new age twist’ on a previous corneal refractive concept that has been utilized in the past but abandoned due to better techniques, specifically excimer laser refractive procedures.” The “new age twist” that Dr. Doane referred to is the use of the femtosecond laser in this technique, and the “corneal refractive concept” is the removal of a convex-shaped lenticule of tissue from within the corneal stroma to flatten the central cornea and reduce myopia. SMILE requires certain characteristics of the femtosecond laser for it to work correctly. Dr. Doane said the laser needs to have a high numerical aperture. This means the x, y, and z spot placement of photodisruption must be exquisite, he said. “If this is achieved, near perfect depth placement of contiguous spots can occur at the lowest single spot energy, and thus excimer laser-like refractive precision can be achieved.” This is a tall order for a femtosecond delivery system, he said. Where do we stand in the FDA trials? SMILE is being studied in the U.S. at 5 centers. In addition to Dr. Thompson and Dr. Doane, the investigational centers are with William Culbertson, MD , and Sonia Yoo, MD , Miami, Fla., U.S.; John Vukich, MD , Madison, Wis., U.S.; and Jon Dishler, MD , Greenwood Village, Colo., U.S. “Patients enrolled in the study have spherical myopia in the range of –1 to –10 D and up to –0.50 D cylinder, although cylinder is not being treated,” Dr. Thompson said. SMILE is performed in one eye, and the non-study eye is treated with LASIK. “We have been impressed with the accuracy of the SMILE procedure,” he said. Preliminary clinical trial results were presented at the 2014 ASCRS•ASOA Symposium & Congress, representing data from 315 eyes. So far, refractive predictability has been impressive in the study. Some risks identified were loss of suction and difficult lenticule removal without tissue loss with retained tissue. The enrollment goal in the clinical trial is 340 eyes, Dr. Thompson said. Advantages of SMILE Dr. Thompson said that the