Central corneal sensitivity after small incision lenticule extraction versus femtosecond laser-assisted LASIK for myopia: a meta-analysis of comparative studies

BACKGROUND The aim of this study was to evaluate central corneal sensitivity after small incision lenticule extraction (SMILE) versus femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) for myopia. METHODS Eligible studies were identified by systematically searching PubMed, the Cochrane Library, Embase and the Chinese Biomedicine Database. Central corneal sensitivity after SMILE versus FS-LASIK was assessed by the pooled weighted mean differences (WMDs) of the reduction from pre-operation levels to 1 week, 1, 3 and 6 months following the operation. The quality of the included literature was assessed by the Quality Index. Data were synthesized by Stata 12.0 SE for Windows. RESULTS Five studies involving 245 patients (363 eyes; 189 eyes in the FS-LASIK group and 174 eyes in the SMILE group) were included in the meta-analysis. The pooled results showed that there were no significant differences in central corneal sensitivity between FS-LASIK and SMILE before surgery (WMD = 0 mm, 95 % CI: -0.23 to -0.23, p = 0.998). At 1 week, 1 and 3 months after surgery, the central corneal sensitivity after FS-LASIK was lower than with SMILE (WMD = -17.35 mm, 95 % CI: -26.54 to -8.16, p <0.001; WMD = -17.52 mm, 95 % CI: -25.10 to -9.94, p <0.001; WMD = -14.64 mm, 95 % CI: -20.08 to -9.21, p <0.001, respectively). However, central corneal sensitivity after FS-LASIK was similar with SMILE 6 months after surgery (WMD = -2.02 mm, 95 % CI: -4.23 to 0.19, p = 0.074). CONCLUSION Central corneal sensitivity exhibited a small decrease and a faster recovery after the SMILE procedure compared to FS-LASIK during the first three postoperative months. Corneal sensitivity after SMILE and FS-LASIK was similar at 6 months after surgery. However, these results should be interpreted with caution due to the limited number of studies.