AIM:To compare dry eye symptoms and signs before and after three kinds surgery, femtosecond laser-assisted laser in situ keratomileusis(FS-LASIK), transepithelial photorefractive keratectomy(T-PRK), small incision lenticule extraction(SMILE)using ocular surface analyzer(Oculus Keratograph).

METHODS:Totally 98 patients(196 eyes)undergoing corneal refractive surgery from January 2017 to May 2017 were recruited. They were divided into three groups, namely, FS-LASIK group, T-PRK group and SMILE group. All patients underwent observation and assessment in the following order: ocular surface disease index(OSDI), tear meniscus height(TMH), measure using the infrared pattern of Oculus Keratograph. The first tear film break-up time(FBUT)and average tear break-up time(ABUT)measure using the infrared pattern of Oculus Keratograph, corneal fluorescein staining(FL), Schirmer Ⅰ test(SⅠt).

RESULTS:1)OSDI index: There was statistically significant difference between the three groups(F_groups=2.799, P_groups<0.05). However, the difference in the OSDI values of different time points in each group was statistically significant(F_time=85.942, P_time<0.001). The OSDI index were significantly increased at 1wk, 1 and 3mo after operation in each group. All groups recovered to the preoperative level at 6mo after operation. After 3mo, there was an inter-group difference in the OSDI values(P=0.019), and the OSDI values of the T-PRK group were higher than those of the other two groups. 2)TMH: There was statistically significant difference among the three groups postoperatively(F_groups=1.720, P_groups<0.05). The TMH values of different time points in each group were significantly different(F_time=11.202, P_time<0.001). The TMH values of each group were significantly reduced after 1wk and 1mo and were restored to preoperative levels after 3 and 6mo. After 3mo, there was a difference TMH among the three groups(P=0.004), and the inferior TMH in the SMILE group was higher than that of the other two groups. 3)FBUT: There was statistically significant difference among the three groups after surgery(F_groups=1.428, P_groups=0.245). The difference in FBUT values between different time points in each group was statistically significant(F_time=4.511, P_time=0.001). The FBUT values of each group were significantly reduced after 1wk and 1mo, and recovered to preoperative levels after 3mo and 6mo. There was no significant difference in FBUT between different groups at each time points(P>0.05). 4)ABUT: There was statistically significant difference in ABUT among the three groups after surgery(F_groups=1.290, P_groups<0.05). However, the difference in ABUT values between different time points in each group was statistically significant(F_time=10.294, P_time<0.001). The ABUT values of each group were significantly reduced after 1wk and 1mo, and recovered to preoperative levels after 3mo and 6mo. There was a statistical difference in ABUT values between different groups after 1mo(P=0.008); among them, the ABUT value of the SMILE group was higher than that of the T-PRK group and the FS-LASIK group. 5)FL: There was no statistical difference in the FL score between the three groups(F_groups=0.816, P_groups=0.445). The differences in the FL scores at different points in each group were statistically significant(F_time=5.539, P_time=0.004). The FL score of each group was significantly higher than before surgery at 1wk and 1mo, and recovered to preoperative levels at 3mo and 6mo after surgery. There was no statistical difference in the FLs between different groups at different points in time(P>0.05). 6)SⅠt: There was no statistically significant difference in SⅠt values among the three groups after surgery(F_groups=0.225, P_groups=0.799). The difference in SⅠt values between different time points in each group was statistically significant(F_time=4.604, P_time=0.003). The SⅠt values of each group were slightly higher than the preoperative values afyer 1wk and 3mo, but they were all within normal values. There was no significant difference between the SⅠt values of 1mo or 6mo after operation and the preoperative level. There was no statistical difference in SⅠt values between different groups at each points in time(P>0.05).

CONCLUSION:The three types of corneal refractive surgery FS-LASIK, T-PRK, and SMILE all cause different degrees of dry eyes within a certain period of time after surgery, but they can gradually recover later. After SMILE surgery, the stability of the tear film recovered faster, while the symptoms after T-PRK surgery improved the least.