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

AIM: To evaluate the possible differences in visual quality between small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK) for myopia.

METHODS: A Meta-analysis was performed. Patients were from previously reported comparative studies treated with SMILE versus FS-LASIK. The PubMed, EMBASE, Cochrane, Web of Science and Chinese databases ( i.e. WANFANG and CNKI) were searched in Nov. of 2016 using RevMan 5.1 version software. The differences in visual acuity, aberration and biomechanical effects within six months postoperatively were showed. Twenty-seven studies including 4223 eyes were included.

RESULTS: No significant differences were observed between SMILE and FS-LASIK in terms of the proportion of eyes that lost one or more lines of corrected distance visual acuity after surgery ( P =0.14), the proportion of eyes achieving an uncorrected distance visual acuity of 20/20 or better ( P =0.43), the final refractive spherical equivalent ( P =0.89), the refractive spherical equivalent within ±1.00 diopter of the target values ( P =0.80), vertical coma ( P =0.45) and horizontal coma ( P =0.06). Compared with the FS-LASIK group, total higher-order aberration ( P <0.001) and spherical aberration ( P <0.001) were higher and the decrease in corneal hysteresis ( P =0.0005) and corneal resistance factor ( P =0.02) were lower in the SMILE group.

CONCLUSION: SMILE and FS-LASIK are comparable in efficacy, safety and predictability for correcting myopia. However, the aberration in the SMILE group is superior to that in the FS-LASIK group, and the loss of biomechanical effects may occur less frequently after SMILE than after FS-LASIK.