Three-year results of small incision lenticule extraction and wavefront-guided femtosecond laser-assisted laser in situ keratomileusis for correction of high myopia and myopic astigmatism

AIM: To compare and calculate the 3-year refractive results, higher-order aberrations(HOAs), contrast sensitivity(CS) and dry eye parameters after small incision lenticule extraction(SMILE) and wavefront-guided femtosecond laser-assisted laser in situ keratomileusis(FS-LASIK) for correction of high myopia and myopic astigmatism.METHODS: In this prospective, non-randomized comparative study, 78 eyes with spherical equivalent(SE) of-8.11±1.09 diopters(D) received a SMILE surgery, and 65 eyes with SE of-8.05±1.12 D received a wavefront-guided FS-LASIK surgery with the Visu Max femtosecond laser(Carl Zeiss Meditec, Jena, Germany) for flap cutting. Visual acuity, manifest refraction, CS, HOAs, ocular surface disease index(OSDI) and tear break-up time(TBUT) were evaluated during a 3-year follow-up.RESULTS: The difference of uncorrected distance visual acuity(UDVA) postoperatively was achieved at 1 mo and at3 mo, whereas the difference of the mean UDVA between two groups at 3 y were not statistically significant(t=-1.59,P=0.13). The postoperative change of SE was 0.89 D in the FS-LASIK group(t=5.76, P=0.00), and 0.14 D in the SMILE group(t=0.54, P=0.59) from 1 mo to 3 y after surgery.At 3-year postoperatively, both HOAs and spherical aberrations in the SMILE group were obviously less than those in the FS-LASIK group(P=0.00), but the coma root mean square(RMS) was higher in the SMILE group(0.59±0.26) than in the FS-LASIK group(0.29±0.14, P=0.00).The mesopic CS values between two groups were not statistically significant at 3 y postoperatively. Comparedwith the FS-LASIK group, lower OSDI scores and longer TBUT values were found in the SMILE group at 1 mo and 3 mo postoperatively. With regard to safety, no eye lost any line of CDVA in both groups at 3 y after surgery. CONCLUSION: Both SMILE and wavefront-guided FSLASIK procedures provide good visual outcomes. Both procedures are effective and safe, but SMILE surgery achieve more stable long-term refractive outcome and better control of early postoperative dry eye as compared to FS-LASIK.