AIM: To study the cutting error of central corneal thickness(CCT)after small incision lenticule extraction(SMILE)in patients with different degrees of myopia.

METHODS: Myopic patients who had undergone SMILE surgery from May 2020 to September 2020 at the Jiangsu Province Hospital were included in the study. Data were organized by refractive status into low, moderate, and high myopia groups. The CCT was measured by the Pentacam anterior segment analysis system preoperatively and postoperatively at 1 and 3mo. Among different myopia groups, the cutting error(ΔCCT, defined as the difference between actual CCT and the predicted CCT)was calculated simultaneously during each visit. The difference ratio of ΔCCT and the relationship between ΔCCT, CCT, and cutting diameter were analyzed.

RESULTS: There were 221 patients(432 eyes)included in our study. At 3mo after operation, the ΔCCT in the high myopia group was larger than the low and moderate myopia group(χ²=225.74, 62.55; all P<0.01), and the moderate myopia group was larger than the low myopia group(χ²=132.77, P<0.01). The cutting deviation rate was also significantly different among three groups at 1 and 3mo after surgery. Pearson correlation analysis found that there was a linear regression relationship among preoperative refractive power, optical zone diameter and the central corneal cutting error at 3mo after operation(r=0.699, P<0.001; r=0.572, P<0.001).

CONCLUSION: The ΔCCT after SMILE increased with the increased of myopia, and the cutting error was positively correlated with preoperative equivalent spherical power and optical zone diameter.