准分子激光原位角膜磨镶术对近视眼高阶像差的影响

Influence of LASIK on higher order aberrations of myopic eyes

目的 :观察并分析准分子激光原位角膜磨镶术(LASIK)对近视患者的波前像差 ,尤其是眼高阶像差的影响 ,探讨术后眼高阶像差与角膜屈光力、角膜厚度的关系。方法 :应用波前像差仪对 33例 ( 6 4只眼 )近视患者LASIK手术前及术后 1个月、1 0个月的眼波前像差进行测量 ;用裂隙扫描式角膜地形图进行手术前后的K1、K2及角膜厚度检查 ,将术前术后的高阶像差、K1、K2及角膜厚度分别进行比较分析。结果 :①LASIK术前的波前像差分布以低阶像差占优势 ,为 81 .7% ,彗差和其他高阶像差分别占 1 3.9%和 4 .4 %。②LASIK术后 1个月高阶像差显著增加 ,差异有显著性(P <0 .0 0 1 ) ,彗差和其他高阶像差分别占 51 .8%和 2 0 .9% ,低阶像差占 2 7.8% ,高阶像差整体平均增加 2 .96倍 ,以二次彗差增加最多 ,达到 3.1 7倍 (P <0 .0 0 1 )。③LASIK术后 1 0个月彗差和其他高阶像差分别占 4 0 .8%和 1 7.0 % ,低阶像差占 38.1 % ,与术后 1个月相比 ,高阶像差均有所减少 ,差异有显著性 (P <0 .0 0 1 ) ,与术前相比 ,整体高阶像差差异仍有显著性 (P <0 .0 1 ) ,表现为二次彗差和二次球差仍比术前有显著增加 ,差异有显著性 (P <0 .0 0 1 ) ,但优势高阶像差彗差、球差逐渐恢复到术前水平 ,差异无显著性 (P >0 .0 5)。

Objective:To observe and analyze the influence of LASIK on higher order aberrations in myopic eyes. To discuss the correlation between higher order aberrations and corneal refractive power (K1,K2),and the correlation between higher order aberrations and corneal thickness.Methods:Sixty four myopic eyes (33 cases) were evaluated by the Allegretto Wave Analyzer at pre LASIK,and 1 month and 10 months after LASIK. The root mean square (RMS) values of higher order aberrations were calculated for each eye when the pupil was dilated. Corneal refractive power and corneal thickness were measured by an Orbascan Ⅱ and corneal topography was assessed at the time of each examination.Results:Before LASIK,the constituent ratio of lower order aberrations was 81.7%,and coma and other higher order aberrations accounted for 13.9% and 4.4%,respectively. One month after surgery,higher order aberrations had increased significantly (P<0.05). The constituent ratios of lower order aberrations and coma and other higher order aberrations were 27.8%,51.8%,and 20.9%,respectively. Ten months after LASIK,higher order aberrations had decreased with the constituent ratios of lower order aberrations,coma and other higher order aberrations. Their respective values were 38.1%,40.8%,and 17.0%. Coma and spherical aberrations returned to preoperative levels. There was a significant positive correlation between severity of myopia and the total number of higher order aberrations after surgery (P<0.05). There was no significant correlation between the total number of higher order aberrations and corneal refractive power or corneal thickness preoperatively (P>0.05),but the correlation became significant after surgery (P<0.01).Conclusion:Conventional LASIK increases higher order aberrations. Higher order aberrations after surgery may tend to decrease with time. The higher the myopia was,the number of higher order aberrations were much greater after surgery.