LASIK术后出现视觉不良症状者的高阶像差分析

Higher-order aberrations in eyes with visual symptoms after LASIK

目的分析经传统准分子激光原位角膜磨镶术（LASIK）或者波前像差引导的LASIK术后患者中（除外过矫、欠矫和眼部疾患导致的视力下降），出现视觉不良症状者的高阶像差分布特征。方法回顾性病例对照研究。本研究回顾了北京军区总医院2006年1月1日至2010年3月31日期间经初次LASIK术后（包括传统组和波前像差引导组），除外过矫、欠矫和眼表及眼内疾患导致的视力下降，出现重影和星芒等视觉症状患者总40例（48眼），传统LASIK组18例（23眼），波前像差引导的LASIK组22例（25眼）。两组患者术后均复诊3个月以上，屈光度稳定在±1．00D以内。所有患者采用WaveScan3．62版波前像差仪，在自然瞳孔下行波前像差检查，提取4mm瞳孔直径高阶像差结果。采用配对样本t检验、配对样本秩和检验、独立样本t检验、独立样本秩和检验及卡方检验对数据进行比较。结果波前像差引导LASIK组高阶像差手术前后比较差异均有统计学意义：总高阶像差均方根（RMS）值术后增加了1．18倍（t=-11．485，P〈0．01）；三阶像差RMS值术后增长了1．25倍（Z=-6．125，P〈0．01）；四阶像差RMS值术后增长了0．93倍（Z=-6．154，P〈0．01）；五阶像差增长了1．35倍（Z=-6．154，P〈0．01）；六阶像差增长了1．14倍（t=-21．080，P〈0．01）。垂直彗差增加了1．43倍（Z=-6．154，P〈0．01）、水平彗差增加了93％（Z=-6．154，P〈0．01）、球差增加了89％（f=-19．659，P〈0．01）。但术后30度三叶草仅增加了5％（Z=-6．154，P〈0．01）、0度三叶草增加了35％（Z=-6．154，P〈0．01）。波前像差引导组术后与传统组术后的比较：总高阶像差、三阶像差、四阶像差、垂直彗差、水平彗差、球差、30度三叶草和0度三叶草比较差异无统计学意义。但两组术后五阶像差陆-2．033，P=0．042）、六阶像差（Z--2．631，P=-0．009）比较差异有统计学意义。另外，两种LASIK术后总高阶像差中，三阶像差所占的比重最大，四阶像差占总高阶像差比例居于第二位。两组比较差异无统计学意义。但两组的五阶像差占总高阶像差比例（Z=-2．053，P=0．040）和六阶像差占总高阶像差比例（Z=-2．012，P=0．044）差异有统计学意义。波前引导组手术前后彗差占三阶像差的56％左右，球差占四阶像差的78％左右，手术前后保持稳定；但三叶草占三阶像差的比例由术前的43％降至术后的36％，手术前后比较差异有统计学意义（t=2．285，P=0．027）。主导像差分布：波前引导组术后垂直彗差为44％、水平彗差为12％、球差为40％，与术前差异有统计学意义（X^2=7．891，P=0．048）。传统组术后垂直彗差占30％、水平彗差占34％、球差为21％，与波前引导组比较差异无统计学意义。结论LASIK术后出现的视觉主诉与高阶像差均方根值增加密切相关。此类患者术后总高阶像差和各类高阶像差的均方根值较术前普遍增加1倍左右（三叶草像差增长较少）。总高阶像差中以三阶像差和四阶像差为主，其中三阶彗差和四阶球差所占的比重最大，三叶草像差所占的比重较小且手术前后有变化。传统LASIK对五阶像差和六阶像差的消融要优于波前像差引导LASIK。LASIK术后的视觉质量下降患者的主导像差类型以彗差和球差居多。

Objective To investigate the distribution of the eye＇s higher order aberrations in post-laser in situ keratomileusis （LASIK） patients with visual complaints, excluding patients whose complaints were due to overcorrection, undercorrection and eye disease. Methods Refractive surgery was performed on 17 625 eyes of 8848 patients from January l, 2006 to March 31, 2010 in BeijingMilitary General Hospital. In this retrospective case-control study, a total of 48 eyes of 40 cases with double vision, glare and other visual symptoms after LASIK （including the traditional group and wavefront-guided group）, excluding cases of overcorreetion, undercorrection and eye disease were reviewed. As a result, there were 23 eyes of 18 cases in the traditional LASIK group and 25 eyes of 22 cases in the wavefront-guided LASIK group. Patients were observed for more than 3 months and refractive power stability was within the ±1.00 D range in both groups. The observation period for thewavefront-guided group was 10 months （4-26 months） and was 23 months for the traditional group （5-72 months）. All patients were measured using a Hartmann-Shaek wavefront sensor. The results for higher-order aberrations with 4-mm pupils were analyzed. The preoperative and postoperative results of the wavefront-guided LASIK group were compared （using a paired samples t test and Wilcoxon signed ranks test）. The results between the wavefront-guided LASIK and traditionalLASIK groups were also compared （using independent samples t tests and the Mann-Whitney test） to test for higher-order aberration root mean square （RMS） values, the distribution ratio of different aberration types in total higher-order aberrations and the dominant aberration changes （chi-square test）. Results There were significant differences in LASIK group when aberrations were compared before higher-order aberrations in the wavefront-guided and after surgery： there was an 118% increasein total higher order aberrations （t=-11.485, P〈0.01）; there was a 125% increase in third order aberration RMS values （Z=-6.125, P〈0.01）; there was a 93% increase in fourth order aberration RMS values （Z=-6.154, P〈0.01）; there was a 135% increase in fifth order aberrations （Z=-6.154, P〈0.01）; there was a 114% increase in sixth order aberrations （t=-21.080, P〈0.01）. Vertical coma increased by 143% （Z=-6.154, P〈0.01）, horizontal coma increased by 93% （Z=-6.154, P〈0.01）, and spherical aberrations increased by 89% （t=-19.659, P〈0.01）. Trefoil varied less than the other types.30° trefoil increased by 5% （Z=-6.154, P〈0.01） and 0° trefoil increased by 35% （Z=-6.154, P〈0.01）. The results for the wavefront-guided LASIK group and the traditional LASIK group were also compared. Differences in total higer-order aberrations, third order aberrations, fourth order aberrations, vertical coma, horizontal coma, spherical aberration, 30° trefoil and 0° trefoilwere 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） showed statistically significant differences when the two groups were compared. In addition, the proportion of third order aberrations was the highest among total higherorderaberrations and fourth order aberrations were second after LASIK. The differences between the two groups were not significant. But the differences in the proportion of fifth order aberrations （Z=-2.053, P=0.040） and sixth order aberrations （Z=-2.012, P=0.044） were statistically significant between the two groups. Coma aberrations accounted for 56% of the third order aberrations and spherical aberration accounted for 78% of the fourth order aberrations before and after wavefront-guided LASIK. But trefoil decreased significantly from 43% to 36% of the third order aberrations after wavefront-guided LASIK （t=2.285, P=-0.027）. The proportion of vertical coma was 44%, horizontal coma was 12% and spherical aberration was 40% among the dominant aberrations after wavefront-guided LASIK and the differencesbetween preoperative and postoperative levels were statistically significant （X^2=7.891, P=0.048）. The proportion of vertical coma was 30%, horizontal coma was 34% and spherical aberration was 21% among the dominant aberrations after traditional LASIK. There were no statistically significant differences between the two groups. Conclusion Visual complaints after EASIK are closely related to the increase in higher-order aberrations. The RMS values of higher-order aberrations are generally higher than preoperative levels except for trefoil aberrations. The third order aberrations and the fourthorder aberrations account for a large proportion of the higher-order aberrations. Coma and spherical aberration are especially important. Trefoil varis less than other types. Traditional LASIK is superior to wavefront-guided LASIK on the ablation of fifth order and sixth order aberrations. Coma and spherical aberration are the dominant aberrations in patients with visual symptoms after LASIK.