The Higher Order Aberrations In Eyes With Visual Symptoms After LASIK

Objective: To investigate the distribution of the eye's higher-order aberrations in post-LASIK patients with visual complaints, excluding the reasons for overcorrection, under correction and eye diseases.Method: There were 17625 eyes of 8848 patients with refractive surgery from January 1, 2006 to March 31, 2010 in Beijing Military General Hospital, which were 7150 eyes of 3592 patients by traditional LASIK and 10475 eyes of 5256 patients by wavefront guided LASIK surgery. In this study, we reviewed total 48 eyes of 40 cases with double vision, glare and other visual symptoms after the LASIK surgery (including traditional group and wavefront guided group), excepting for overcorrection, under correction and eye diseases. Traditional LASIK (LASIK) group was 23 eyes of 18 cases and wavefront guided LASIK (wfg-LASIK) group was 25 eyes of 22 cases. Patients were observed more than 3 months with refractive power stability within the±1.0D of both groups. The observed period in wavefront-guided group was 10 months (minimum 4 months, up to 2 years 2 months)and 23 months in the traditional group (minimum 5 Month, up to 6 years) . All the patients were measured using a Hartmann-Shack wavefront sensor ( WaveScan 3.62 ,AMO,NY). Analysis results of the higher-order aberrations with a 6-mm pupil. The preoperative and postoperative results of wavefront guided LASIK group were compared (using paired sample t test and wilcoxon signed ranks test). The results between wavefront guided LASIK with conventional LASIK group were also compared (using two independent samples t test and mann-whitney test), including higher order aberration RMS value, the distribution ratio of different aberration types in total higher-order aberrations and the dominant aberration change (chi-square test).Result: There were significant differences in the higher-order aberrations before and after Wavefront guided LASIK group, the total higher-order aberrations was an increase of 1.18 times (t =- 11.485, P = 0.000); third order aberration RMS value was an increase of 1.25 times (Z =- 6.125, P = 0.000); fourth order aberration RMS value was an increase of 0.93 times (Z =- 6.154, P = 0.000); fifth order aberrations increased by 1.35 times (Z =- 6.154, P = 0.000); sixth order aberrations increased by 1.14 times (t =- 21.080, P = 0.000),vertical coma increased 1.43 times (Z =- 6.154, P = 0.000), horizontal coma increased 0.93 times (Z =- 6.154, P = 0.000), spherical aberration increased by 0.89 times (t =- 19.659, P = 0.000).However, Trefoil varies less than other types.30°trefoil was an increased 5% (Z =- 6.154, P = 0.000) and 0°trefoil was an increased 35% (Z =- 6.154, P = 0.000). The results between wavefront guided LASIK with traditional LASIK group were also compared. Total high order aberrations (t = 0.100, P = 0.920), third order aberrations (Z =- 0.691, P = 0.489), fourth order aberrations (t = 0.429, P = 0.670), vertical coma (Z =- 0.093, P = 0.926), horizontal coma (Z =- 1.950, P = 0.051), spherical aberration (t = 0.207, P = 0.837), 30°trefoil (Z =- 0.939, P = 0.348) and 0°trefoil (Z =- 0.031, P = 0.975) were not statistically significant. But the postoperative fifth order aberrations (Z =- 2.033, P = 0.042) and sixth order aberrations (Z =- 2.631, P = 0.009) of two groups was statistically significant. In addition, third order aberration was the largest share in total high order aberration and fourth order aberration was in second place after LASIK. There were not statistically significant between two groups. But proportion of fifth order aberration (Z =- 2.053, P = 0.040) and sixth order aberrations (Z =- 2.012, P = 0.044) were statistically significant between two groups. The proportion of coma aberrations in third order aberration accounted for 58%, and spherical aberration in fourth order aberrations was 78% before and after Wavefront-guided LASIK. But the trefoil in third-order aberrations decreased significantly from 52% to 36% after Wavefront-guided LASIK (t = 2.285, P = 0.027). The proportion of vertical coma was 44% and spherical aberration was 40% in the dominant aberration after Wavefront-guided LASIK, there was statistically significant between pre-operational with post-operation (χ~2=7.891, P = 0.048). The horizontal coma was 34%, vertical coma was 30% and spherical aberration was 21% in the dominant aberration after traditional LASIK, there was no statistically significant between two group(χ~2 =5.755,P=0.124).Conclusion: The patients with visual complaints after LASIK are closely related with the increasing of higher order aberrations. The RMS values of higher order aberrations were generally higher than the preoperative about 1 time except for Trefoil aberrations. The third-order aberrations and the fourth-order aberrations occupied a larger proportion in higher order aberrations. Coma and spherical aberration was the largest share especially. Traditional LASIK is superior to wavefront guided LASIK on the ablation of fifth order and sixth order aberrations. The dominant aberration of the patients with visual complaints after LASIK was mainly for coma aberration or spherical aberration and the proportion of trefoil decreased sharply.