ObjectiveTo evaluate the effectiveness of using a six-dimensional eye-tracking system during femtosecond laser-assisted sub-Bowman keratomileusis (FS-SBK) surgery to correct myopia and astigmatism. MethodsA total of 23 patients (36 eyes) with ametropia undergoing FS-SBK were retrospectively analyzed and divided into the static cyclotorsion control (SCC) group (11 patients, 20 eyes) and the non-SCC group (12 patients, 16 eyes). According to the static eyeball rotation degrees, the SCC group was further divided into three subgroups: within ±2° group (5 patients, 9 eyes), ±2°-±5° group (4 patients, 7 eyes), and above ±5° group (2 patients, 4 eyes). The preoprative and postoperative one-month uncorrected visual acuity, best corrected visual acuity, diopter of spherical power, diopter of cylindrical power, corneal curvature, and the rotating degree in SCC were observed; the root-mean-square values of the total higher-order aberrations, spherical aberration, coma, Strehl ratio, etc. when the pupil diameter was 6.5 mm were extracted; and the therapeutic efficacy was observed. ResultsNo severe intraoperative or postoperative complications occurred in any subject. The effectiveness index of the SCC group was 0.947±0.145, and that of the non-SCC group was 1.005±0.141, with no statistically significant difference (P>0.05). Compared with the preoperative levels, in the two groups, the postoperative uncorrected visual acuity was significantly elevated; the postoperative diopter of spherical power, diopter of cylindrical power, and corneal curvature difference were reduced; the postoperative total higher-order aberrations, spherical aberration, and coma increased; all the differences mentioned above were statistically significant (P<0.05). In the SCC group, the difference between the preoperative and the postoperative Strehl ratio was statistically significant (P<0.05). There was no significant difference in postoperative indicators between the SCC group and the non-SCC group (P>0.05). The difference in postoperative increment of coma between the SCC group and the non-SCC group was statistically significant (P<0.05). In the SCC group, no statistically significant difference was found in postoperative increment of any indicator among the three subgroups (P<0.05). ConclusionsFS-SBK of six-dimensional eye-tracking system is effective in correcting myopia and astigmatism. FS-SBK can reduce lower-order aberrations while introducing higher-order aberrations, and whether SCC is performed intraoperatively is meaningless.

Citation： ZHENG Qiongqin, DENG Yingping. Analysis of the efficacy of femtosecond laser-assisted sub-Bowman keratomileusis on the correction of myopia and astigmatism with six dimensional eye tracking system. West China Medical Journal, 2018, 33(11): 1376-1381. doi: 10.7507/1002-0179.201806175 Copy