METHODS: This was a retrospective case study. The patients(76 eyes)with ametropia who had undergone SMILE surgery in our hospital from September 2018 to March 2019 were small age, high degree of severity, thin cornea or irregular shape. The patients were divided into the SMILE combined with CXL group with 17 patients(32 eyes)and the SMILE group with 22 patients(44 eyes). The corneal morphological parameters of the two groups were measured preoperatively and 1mo postoperatively.

RESULTS: There were significant statistically differences in the changes of K1, K2, Km, central corneal thickness, posterior corneal elevation, anterior corneal elevation parameters, posterior corneal elevation parameters, the D value and index of vertical asymmetry(IVA)between these two groups(P<0.05), while there were no significant statistically difference in the changes of index of highest decentration(IHD)(P>0.05). The changes of some parameters of the corneal anterior surface morphology of the two groups were correlated with the corneal cutting depth, spherical equivalent and optical zone diameter(P<0.05). While the changes of some parameters of the corneal posterior surface morphology were not correlated with the corneal cutting depth, spherical equivalent,and optical zone diameter(P>0.05). There was no apparent correlation between the changes of corneal surface morphology and the cross-linking depthin SMILE combined with CXL group(P>0.05).

CONCLUSION: SMILE combined with CXL was applied to the high-risk patients with small age, high degree of severity, thin cornea or irregular shape, which increased its safety and effectiveness. SMILE combined with CXL didn't make significant effects on the posterior surface morphology of the cornea, but it influenced the anterior surface morphology. The influenced factors may be related to the corneal cutting depth, the spherical equivalent and the optical zone diameter.