Comparison of Visual, Refractive and Ocular Surface Outcomes Between Small Incision Lenticule Extraction and Laser-Assisted In Situ Keratomileusis for Myopia and Myopic Astigmatism

Laser-assisted in situ keratomileusis (LASIK) is the most commonly performed laser refractive surgical technique worldwide for the treatment of myopia and myopic astigmatism. In recent years, small incision lenticule extraction (SMILE) has emerged as a promising alternative to LASIK, requiring only a single femtosecond laser to create an intrastromal lenticule, which is then removed via a small incision. The technique obviates the need for a corneal flap. A number of published studies have compared the two techniques in terms of visual, refractive and ocular surface outcomes. This review compares the clinical outcomes between LASIK and SMILE in treating myopia and myopic astigmatism based on studies published in the last 5 years. Twenty-two studies were included, all of which were observational in nature. Results suggest that the two techniques have comparable visual outcomes in terms of safety, efficacy and predictability, although recovery in visual acuity may be slower in SMILE-treated than LASIK-treated eyes. SMILE is found to result in less severe postoperative dry eye symptoms and faster recovery of corneal sensitivity than LASIK. It is important to note, however, that the SMILE technique is limited by the lack of a cyclotorsion-compensation system and option for customized treatment profile. The heterogeneity of results in this review may be attributable to the use of different LASIK platforms in different studies. Few studies compared the outcomes regarding severity of myopia. Future prospective randomized controlled trials with a larger sample size and longer follow-up period will be highly beneficial for progress in this field.