近视眼角膜前表面形态与角膜高阶像差的相关分析

目的 探讨近视眼角膜前表面形态(角膜曲率、高度、非球面性)与角膜高阶像差的相关关系.方法 横断面研究.近视患者57例(57眼),球镜度-1.50～-6.00D,平均(-3.88±1.12)D,柱镜度0～-3.50 D,平均(-0.59±0.58)D,应用Pentacam眼前节分析仪,获取角膜表面变异系数(ISV)、角膜高度的非对称指数(IHA)、非球面系数(Q值)及角膜前表面像差,应用Pearson相关分析ISV、IHA和Q值与角膜高阶像差的相关关系.结果 ISV与角膜垂直彗差(Z3-1)、水平彗差(Z3+1)均呈正相关(r=0.389,P=0.003;r=0.594,P＜0.001),与角膜球差(Z40)呈负相关(r=-0.400,P=0.002);ISV与角膜的三阶像差(S3)呈正相关(r=0.683.P＜0.001),与角膜的四阶像差(S4)呈负相关(r=-0.373,P=0.004).IHA与Z3-1、S3呈正相关(r=0.446,P＜0.001;r=0.445,P＜0.001).Q值与Z40、S4呈正相关(r=0.849,P＜0.001;r=0.761,P＜0.001),与角膜的五阶像差(S5)呈负相关(r=0.280,P=0.035).结论 角膜表面曲率变异越大,角膜的三阶像差越大.角膜表面高度上下越不对称,角膜垂直彗差越大.Q值越大,即角膜形状越偏向扁椭圆形,角膜球差越大.

Correlation analysis between anterior corneal surface shape and corneal higher-order aberrations

Objective To investigate the correlation between anterior corneal surface shape (including corneal curvature, corneal height, and asphericity) and corneal higher-order aberrations. Methods In this cross-sectional study, 57 eyes of 57 myopic subjects were included. The mean spherical refractive error was (-3.88±1.12)D (range-1.50--6.00 D) and cylinder was (-0.59±0.58)D (range 0--3.50 D). Anterior corneal surface shape was measured with a Pentacam (Oculus, Wetzlar, Germany) and index of surface variance (ISV), index of height asymmetry (IHA), aspheric index (Q-value) and anterior comeal aberrations were analyzed. A Pearson correlation analysis was used to assess the correlations between ISV, IHA, Q-value and anterior corneal higher-order aberrations. Results ISV had a significantly positive correlation with corneal vertical coma (Z3-1) and horizontal coma (Z3+1) (r=0.389, P=0.003; r=0.594, P＜0.001). A negative correlation was found between ISV and corneal spherical aberrations (Z40) (r=-0.400, P=0.002). ISV was positively correlated with comeal 3rd-order aberrations (S3) (r=0.683, P<0.001) but showed a negative correlation with corneal 4*-order aberrations (S4) (r=-0.373, P=0.004). IHA was positively correlated with comeal Z3-1 and S3 (r=0.446, P＜0.001; r=0.445, P<0.001). The Q-value showed a significant positive correlation with comeal Z40 and S4 (r=0.849, P＜0.001; r=0.761, P＜0.001). A negative correlation was found between the Q-value and 5th-order aberrations (r=-0.280, P=0.035). Conclusion Comeal 3rd-order aberrations increase with comeal surface curvature variance. Comeal vertical coma increases with the asymmetry of comeal upper and lower height. Comeal spherical aberrations increase as the anterior comeal surface shows more oblateness.