近视眼高阶像差在低阶像差矫正后的变化

Changes in higher-order aberrations after correction of lower -order aberrations in myopic eyes

目的探讨矫正近视眼低阶像差对高阶像差的影响,重点分析其对球差、彗差和三叶草的影响。方法应用基于Hartmann-Shack传感器的波前像差仪分别测量34例(63眼)近视患者的,用球镜及柱镜矫正屈光不正前、后的高阶像差,依据屈光状态分为单纯近视组10例(18眼),近视低度散光组13例(26眼)(散光≤-0.50D)和近视中度散光组11例(19眼)(-0.50D<散光<-1.00D)。采用SPSS13.0统计软件对波前像差的均方根和各Zernike项系数进行统计学处理。结果屈光不正矫正后,单纯近视组C40由矫正前的(0.05±0.12)μm变为(0.01±0.14)μm,差异有统计学意义(t=2.770,P=0.022),其他各项差异均无统计学意义(P>0.05);近视低度散光组各Zernike项系数差异均无统计学意义(P>0.05);近视中度散光组C40无显著性变化,由矫正前的(0.12±0.14)μm变为(0.11±0.17)μm(t=0.072,P=0.944),而C31由矫正前的(-0.01±0.17)μm变为(0.03±0.17)μm(t=-2.495,P=0.034),C33由矫正前的(-0.07±0.13)μm变为(-0.09±0.13)μm(t=2.676,P=0.025)。三个屈光度组的高阶像差均方根(RMS)在低阶像差矫正前、后差异均无统计学意义(P>0.05),仅St和S3呈现增加趋势,S4和S5在单纯近视组增加,在近视散光组基本无变化。结论单纯近视者矫正离焦后引起C40的明显变化;近视中度散光者完全矫正屈光不正后呈现C31和C33的显著变化。矫正不同的离焦和散光影响不同的高阶像差。

Objective To evaluate the effect on high-order aberrations of the eye by measuring wavefront aberrations with or without correcting defocus and astigmatism, especially for the effect of spherical aberrations, coma and trefoil. Methods A Hartmann-Shack aberrometer was used to measure wavefront aberrations before and after correcting myopia and astigmatism with sphere and cylinder trial lenses. Sixty-three eyes of 34 patients were divided into three groups based on refractive error： group A, 18 eyes of 10 patients （myopia with no astigmatism）, group B, 26 eyes of 13 patients （myopia with astigmatism not more than -0.50 D） and group C, 19 eyes of 11 patients （myopia with astigmatism greater than -0.50 D and not more than -1.00 D）. The root mean square （RMS） values of the wavefront aberrations and Zenike aberrations were calculated. Results After correcting for myopia, the spherical aberrations （C40） of group A were less than for naked eyes [from （0.05±0.12） μm to （0.01±0.14）μm, t=2.770, P=0.022]. In group B, none of the Zernike coefficients had a significant change after correcting for lower-order aberrations. In group C, the C40 had no significant change （t=0.072, P=0.944）, but the horizontal coma （C31） and the horizontal trefoil （C33） had a statistically significant change, changed from （-0.01±0.17）μm before correction to （0.03±0.17） μm after correction, and C33 changed from （-0.07±0.13）μm before correction to （-0.09±0.13）μm after correction（P=0.034 and 0.025, respectively）. The RMS of each higher-order aberration and total higher-order aberrations showed no statistically significant change （P〉0.05）. The mean RMS of total higher-order aberrations and the third order had a tendency to increase. Conclusion The C40 of myopia subjects has a statistically significant change after correcting defocus with a sphere trial lens. The C31 and C33 of the myopia subjects with moderate astigmatism show statistically significant changes after being fitted with both sphere and moderate cylinder trial lenses. This shows that correcting different amounts of defocus and astigmatism affect different higher-order aberrations.