Clinical outcomes after small incision lenticule extraction versus femtosecond laser-assisted LASIK for high myopia: a Meta-analysis.

Abstract Background To compare postoperative clinical outcomes of high myopia after being treated by Small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK).Methods Comprehensive studies were conducted on the PubMed, MEDLINE, EMBASE, the Cochrane Library, and Chinese databases.Trials meeting the selection criteria were quality appraised, and the data were extracted by 2 independent authors, and the RevMan 5.3 version software were used in analyzing.Result Ten studies involving 637 patients (1093 eyes;575 eyes in the SMILE group and 518 eyes in the FS-LASIK group) were included in this meta-analysis. Pooled result revealed no significant differences in the following outcomes: the logMAR values of postoperative UDVA(WMD = -0.01, 95% CI: -0.02,0.00, I²=0%, P = 0.10 at postoperative 1mo; WMD =-0.01, 95% CI: -0.00 to 0.01, I²=0%,P = 0.35 at postoperative 3mo; WMD = -0.01, 95% CI:-0.02 to 0.01, I²=17%,P = 0.26 at long term), the logMAR values of postoperative CDVA(WMD = -0.02, 95% CI, -0.04 to 0.00, I²=0%, P = 0.11),and the postoperative mean refractive SE (WMD =0.02, 95% CI:0.04 to 0.08, I²=29%, P=0.60) . In the long-term observation, postoperative tHOA (WMD =-0.10, 95% CI:-0.13 to -0.07, I²=15%, P<0.00001)and postoperative spherical aberration (WMD =-0.13, 95% CI:--0.17 to -0.09, I²=38%, P<0.00001) were found to be less in the SMILE group compared with the FS-LASIK group, but no significant difference was found in postoperative coma (WMD =-0.02, 95% CI:-0.04 to 0.00, I²=98%, P=0.40).We also found greater PCE change post FS-LASIK than SMILE at long term follow-ups(WMD =-0.69, 95% CI:-1.36 to -0.01, I²=0%, P<0.05, however, there was no significant difference between the two groups at 3- or 6- months.(WMD =-0.19, 95% CI:-0.41 to 0.03, I²=31%, P=0.09;WMD =-0.20, 95% CI:-0.50 to 0.10, I²=17%, P=0.20)Conclusion For patients with high myopia, both SMILE and FS-LASIK are safe and efficacious. However, SMILE induced less tHOA and spherical aberration compared with FS-LASIK. Besides, FS-LASIK showed a greater increase in PCE than SMILE only at long term follow-ups. It remains to be seen whether the patients can get a better visual quality after SMILE and more comparative studies focused on high myopia is necessary.