Small-incision lenticule extraction (SMILE) was recently approved by the FDA, but it is not yet commercially available in the United States. I anticipate that SMILE will become widely adopted and performed in the future. This will give us another laser vision correction procedure to offer our patients looking for freedom from glasses and contact lenses.
In its initial form, femtosecond lenticule extraction was first reported in 2008 by Sekundo et al.1 In 2010, the same group introduced a modification of the procedure that avoided creating a corneal flap, resulting in the current SMILE technique. Internationally, SMILE has been increasing in popularity, with more than 500,000 procedures performed worldwide, the majority of which have occurred in the past 2 years.
In the procedure, a femtosecond laser is used to create two curved corneal intrastromal incisions in the shape of a lenticule plus an additional sidecut incision. Next, the lenticule is manually dissected free anteriorly and posteriorly, and then it is removed from the cornea through the sidecut.
Thanks to its precision, the VisuMax femtosecond laser (Carl Zeiss Meditec) used for SMILE can correctly create an appropriately sized lenticule to be removed based on the patient’s refractive goal. In using this laser now for LASIK, I have been pleased with its accuracy in flap creation and the ease of dissecting the tissue plane to lift the flap. Efficient tissue cleaving is also important for SMILE because the lenticule dissection is essentially performed within a corneal pocket.
Modern LASIK is a great procedure that is highly effective and safe; SMILE will need to match these results to gain full acceptance. We will know more about SMILE and its long-term results in the future, but early indications are that it is generally comparable to LASIK. With the small incision, fewer corneal nerves are cut compared with LASIK, and the resulting incidence of postoperative dry eye is lower.
There are millions of people who could benefit from laser vision correction, and perhaps the release of SMILE as a new procedure will motivate many prospective patients to explore their options. Time will tell if our predictions come true, but we may look back on the widespread acceptance of SMILE as one of the major developments in laser vision correction along with the initial releases of PRK, LASIK, and femtosecond laser-assisted LASIK.
1. Sekundo W, Kunert K, Russmann C, et al. First efficacy and safety study of femtosecond lenticule extraction for the correction of myopia: six-month results. J Cataract Refract Surg. 2008;34(9):1513-1520.
