Small Incision Lenticule Extraction (SMILE) versus Femtosecond Laser-Assisted In Situ Keratomileusis (FS-LASIK) for Myopia: A Systematic Review and Meta-Analysis

Abstract

PurposeThe goal of this study was to compare small incision lenticule extraction (SMILE) with femtosecond laser-assisted in situ keratomileusis (FS-LASIK) for treating myopia.MethodsThe CENTRAL, EMBASE, PubMed databases and a Chinese database (SinoMed) were searched in May of 2016. Twelve studies with 1,076 eyes, which included three randomized controlled trials (RCTs) and nine cohorts, met our inclusion criteria. The overall quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group framework. Data were extracted and analysed at three to six months postoperatively. Primary outcome measures included a loss of one or more lines of best spectacle corrected visual acuity (BSCVA), uncorrected visual acuity (UCVA) of 20/20 or better, mean logMAR UCVA, postoperative mean spherical equivalent (SE) and postoperative refraction within ±1.0 D of the target refraction. Secondary outcome measures included ocular surface disease index (OSDI), tear breakup time (TBUT) and Schirmer’s 1 test (S1T) as dry eye parameters, along with corneal sensitivity.ResultsThe overall quality of evidence was considered to be low to very low. Pooled results revealed no significant differences between the two groups with regard to a loss of one or more lines in the BSCVA (OR 1.71; 95% CI: 0.81, 3.63; P = 0.16), UCVA of 20/20 or better (OR 0.71; 95% CI: 0.44, 1.15; P = 0.16), logMAR UCVA (MD 0.00; 95% CI: -0.03, 0.04; P = 0.87), postoperative refractive SE (MD -0.00; 95% CI: -0.05, 0.05; P = 0.97) or postoperative refraction within ±1.0 D of the target refraction (OR 0.78; 95% CI: 0.22, 2.77; P = 0.70) within six months postoperatively. The pooled analysis also indicated that the FS-LASIK group suffered more severely from dry eye symptoms (OSDI; MD -6.68; 95% CI: -11.76, -2.00; P = 0.006) and lower corneal sensitivity (MD 12.40; 95% CI: 10.23, 14.56; P < 0.00001) at six months postoperatively.ConclusionsIn conclusion, both FS-LASIK and SMILE are safe, effective and predictable surgical options for treating myopia. However, dry eye symptoms and loss of corneal sensitivity may occur less frequently after SMILE than after FS-LASIK.

Agreement and repeatability of objective systems for assessment of the tear film

“…Symptoms measured with the OSDI are not usually correlated with clinical signs. [7] In spite of the fact that changes in the OSDI and in some clinical signs can be produced after refractive surgery [10] or after treatments,[29] there are not usually correlations between objective measures and subjective questionnaires. Our experiments are consistent with these previous findings, either for VK or OQAS, even though some authors have reported significant non-linear correlations between NIBUT and OSDI.…”

“…Recently, a less invasive technique named SMILE (small incision lenticule extraction) has been proven to reduce the postoperative incidence of dry eye symptoms in comparison to LASIK, although no clear differences in objective clinical signs have been found between procedures. [10] There are numerous diagnostic tests for dry eye that are not widely accepted yet and are often not reproducible, probably due to the complexity of the disease and the high variability between seasons, time, examiners, etc. [11] New technologies have emerged in order to assess objectively the tear film in a non-invasive way.…”

Topography-Guided LASIK Versus Small Incision Lenticule Extraction (SMILE) for Myopia and Myopic Astigmatism: A Randomized, Prospective, Contralateral Eye Study

“…Admittedly initial studies report SMILE efficacy comparable to standard (wavefront-optimized) LASIK showing essentially "equal" postoperative results. [15][16][17][18][19][20][21][22] Investigators recently reported comparable visual outcomes when comparing wavefront-optimized to topography-guided profiles in a contralateral eye study. 26 However, this study did did not use topography-guided modification (TMR) of the clinical refraction in the respective treatments, something that was the backbone of the refractions used in our study herein and may explain the difference in outcomes.…”

Small incision lenticule extraction (SMILE) techniques: patient selection and perspectives

“…SMILE is comparable to femtosecond laser-assisted in situ keratomileusis (FS-LASIK) in terms of safety, efficacy, and predictability. 5 , 6 Moreover, it has the advantages of better ocular surface stability and biomechanical strength compared to FS-LASIK. 6 – 10 It provides precise visual acuity and quality and is increasingly being preferred for the treatment of myopia and myopic astigmatism owing to the enhanced patient satisfaction.…”