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.