AIM: To explore the posterior corneal surface height after femtosecond laser small incision lenticule extraction(SMILE)or femtosecond laser in situ keratomileusis surgery(Fs-LASIK).

METHODS: A retrospective analysis of 113 cases of patients(226 eyes)with myopia underwent laser corneal refractive surgery in our hospital from January to December 2016 was taken. There were 51 cases(102 eyes)with SMILE and 62(124 eyes)with Fs-LASIK. Postoperative posterior corneal surface height, uncorrected visual acuity, spherical equivalent change, operation safety were analyzed and compared between the two groups.

RESULTS: The preoperative posterior corneal surface height had no statistical difference between the two groups(P>0.05). Corneal surface height at 1, 3 and 6mo after operation were significantly higher than those before operation(P<0.05), but the differences between the two groups at different time points after operation were not significant(P>0.05). Preoperative uncorrected visual acuity had no statistical difference between the two groups(P>0.05); postoperative uncorrected visual acuity at 1, 3 and 6mo were significantly better than those before operation(P<0.05), but the differences between the two groups at different time points after operation were not significant(P>0.05). Preoperative spherical equivalent had no statistical difference between the two groups(P>0.05); postoperative spherical equivalent at 1wk were significantly better than those before operation(P<0.05), but the differences between the two groups after operation were not significant(P>0.05). Postoperative incidence of adverse reactions such as corneal edema, corneal infection, diffuse lamellar keratitis and postoperative glare had no statistical difference between the two groups at 6mo after operation(P>0.05).

CONCLUSION: SMILE and Fs-LASIK can be safely and effectively correcting visual acuity, but posterior corneal surface partial forward occurred after either operation.