Purpose:

There are many suggestions about small-incision lenticule extraction (SMILE), including that it has refractive outcomes similar to those of LASIK. However, these have not been clearly substantiated by research. The purpose of this study was to review and compare literature published about SMILE and femtosecond (fs) LASIK.

Methods:

The PubMed database was searched using the terms SMILE and FLEX. Over 120 peer-reviewed scientific papers published between 2010 and 2016 were included in this study. Topics researched include the advantages of SMILE, the claimed but unproven advantages of SMILE, and the disadvantages of SMILE.

Results:

Although it is suggested that SMILE and LASIK patients have comparable refractive visual outcomes, this thorough review of published literature revealed this to be unsubstantiated. Likewise, it has been suggested that SMILE causes fewer high order aberrations (HOAs) to the cornea, but the literature reports no HOA correction. Additional assertions including less ectasia and less postsurgical light scattering in the cornea are also unproven. Instead, it was revealed that visual outcomes for patients undergoing SMILE are worse than of those undergoing LASIK. Furthermore, after hyperopic SMILE, 30% of patients lose one line of CDVA, and SMILE is suboptimal for moderate myopia (< 4D).

Conclusions:

Despite suggestions that SMILE may have comparable visual outcomes to those of LASIK, a systematic review of the literature demonstrates lack of substantiation for such assertions, as well as a number of efficacy-related pitfalls that have been reported about SMILE.