A patient in my San Luis Obispo office asked me about the difference between custom wavefront LASIK and SMILE (small incision lenticular extraction) for laser eye surgery. Both use a laser to reshape the cornea, but they use different types of lasers and use a different surgical approach. With customized wavefront LASIK, a thin flap is lifted from the surface of the cornea, an excimer laser is used to sculpt the underlying cornea, and then the flap is re-positioned to drape over the new shape. With SMILE, a femtosecond laser is used to sculpt out the outlines of a piece of corneal tissue within the cornea. The laser also makes a small incision on the side of the cornea. The precisely shaped piece of corneal tissue is then removed through this small incision with a forceps. The surface of the cornea then sinks into the space created by the removal of the segment of cornea, creating a new contour to the cornea. Customized wavefront LASIK benefits from the fact that the shape the laser inscribes is determined by a wavefront mapping of the optical fingerprint, allowing the surgery to be customized to the individual patient. This approach is not yet available with SMILE so with SMILE the shape of the corneal tissue that is removed is determined by the refraction (the “which is better one or two test”) which is not as accurate as the customized wavefront measurements. A study recently was performed comparing the results of customized wavefront LASIK to SMILE. In this study, 51 patients underwent customized wavefront LASIK using the VISX Star S4IR (the same laser I use) and 59 patients underwent SMILE using the VisuMax femtosecond laser. The LASIK patients had faster visual recovery and better safety as well as better visual quality and less induction of higher order aberrations (HOA’s) than the SMILE patients, although patients from both groups had good outcomes. The author of the study, Dr. Mounir A. Khalifa, concluded “Wavefront Guided LASIK remains the state-of-the-art laser vision correction technique. It offers more predictable outcomes and better aberrometric control and delivers rapid visual recovery and better uncorrected visual acuity.” I agree that customized wavefront LASIK — and its flapless cousin customized wavefront PRK — represent the best in laser vision correction. I do think SMILE is an interesting and promising procedure, but I feel it is still a procedure in evolution.