Cover Focus | Nov/Dec 2016

SMILE: A Closer Look

We first mentioned small incision lenticule extraction (SMILE), a modification of the FLEX procedure, in the July/August 2010 issue.1 Of the advantages described by Jesper Hjortdal, MD, PhD, at that time, the biggest were the potential for greater biomechanical stability and a lower risk of corneal ectasia.

Developments in the procedure were slow, but many surgeons continued to think that it was the refractive treatment of the future. In the April 2012 issue, Sven Asp, MD, DMSci, said that ReLEx SMILE had the potential to become the gold standard in refractive correction. The procedure, he said, “is the most significant development in corneal refractive surgery since the introduction of LASIK.”2

In a 2015 outlook article, Robert Edward Ang, MD, said that, even with the continuation of the flat LASIK market, LASIK would remain the go-to treatment in most centers. Although “more buzz and data on ReLEx SMILE will surface,” he said that the procedure was not yet a must-have.3

Promising results with SMILE had appeared, however. Evaluating the safety of SMILE by calculating postoperative tensile strength, Dan Z. Reinstein, MD, MA, FRCSC, DABO, FRCOphth, FEBO, found that “we can achieve refractive predictability to within ±0.50 D in about 80% of eyes and within ±1.00 D in almost all eyes with low to moderate myopia.” Using a model to compare the removal of 100 µm of stroma with an ablation (LASIK or PRK) versus as a lenticule (SMILE) from a 550-µm thick cornea, he found that “the model calculated the postoperative tensile strength would be 75% of the initial value after SMILE performed with a 130-µm cap, 68% after PRK, and 54% after thin-flap (100 µm) LASIK.”4

Roberta Calienno, MD; Leonardo Mastropasqua, MD; Mario Nubile, MD; and Niccoló Salgari, MD, also reported on clinical advantages of SMILE over LASIK.5 Using laser scanning in vivo confocal microscopy to examine the induced alterations and corneal wound healing patterns in myopic eyes after femtosecond LASIK and SMILE, they found “significantly less surgical denervation in SMILE than in [femtosecond] LASIK,” and they noted that “significantly faster nerve regeneration also seems to occur.”

Jodhbir S. Mehta, FRCS, FRCOphth, said that, with approximately 125,000 SMILE treatments performed globally, results were promising.3 “I believe that, in 2015, we will continue to witness a shift away from conventional LASIK,” he wrote. “Patients have also become more aware of the SMILE procedure over the past 2 years.”

1. Hjortdal J. Refractive lenticule extraction. Accessed November 15, 2016.

2. Asp S. Refractive laser lenticular extraction: A new paradigm. Accessed November 15, 2016.

3. Ang RE, Hanneken L, Holland D, Mehta JS. Trends in refractive surgery and in presbyopia correction. Accessed November 15, 2016.

4. Reinstein DZ. How corneal biomechanics matters in optimizing refractive surgery. Accessed November 15, 2016.

5. Calienno R, Mastropasqua L, Nubile M, Salgar N. Preserving corneal architecture with a flapless technique. Accessed November 16, 2016.

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