近视眼角膜高阶像差的特征及影响因素

An investigation on the characteristics and related factors of corneal higher-order aberration

目的分析角膜高阶像差的分布特点，角膜前表面、后表面与整体角膜高阶像差三者之间的关系，以及相关因素对各项高阶像差的影响。方法横断面研究。随机选择在天津市眼科医院屈光手术中心欲行近视眼准分子激光手术的患者108例，其中男55例，女53例，年龄18—38岁，平均（23．3±4．1）岁；等效球镜度数为-1．38—12．50D，平均（-5．81±2．19）D；应用Pentacam眼前节分析系统采集右眼角膜像差及角膜最薄点厚度（TCT）。采用Mann-Whitney秩和检验和Spearman相关分析。结果近视眼角膜各高阶像差均方根（RMS）值随阶数增加大致呈递减趋势，以三阶和四阶RMS值的数值较大。角膜后表面的波前像差值远远小于前表面，整体角膜RMS值介于角膜前、后表面之间。角膜前表面三阶RMS值、角膜前表面六阶RMS值、角膜后表面五阶RMS值、角膜后表面六阶RMS值、角膜三阶RMS值、角膜六阶RMS值与眼压呈正相关（r=0．217、0．248、0．269、0．210、0．222、0．282，P〈0．05）。高阶像差与TCT之间无相关性。男性与女性各高阶像差之间的差异无明显统计学意义。左右眼高阶像差差异无统计学意义。结论近视眼角膜各高阶像差RMS值随阶数增加大致呈递减趋势。角膜后表面的高阶像差RMS值远远小于角膜前表面，角膜前、后表面像差相互补偿。性别和眼别对角膜高阶像差无明显影响。

Objective To analyze the characteristics and distribution of higher-order aberrations in myopia, and to study the correlation between higher-order aberrations and the anterior and posterior corneas and possible factors that affect it. Methods It was a cross-sectional study. 108 normal patients, including 55 males and 53 females, were recruited in the Refractive Center of Tianjin Eye Hospital. The average age was 23.3±4.1 years （range 18 to 38 years）. The mean spherical diopter was -5.81±2.19 D （range -1.38 to -12.50 D）. Corneal aberration and thinnest corneal thickness were obtained with the Pentacam system. The results were analyzed with SPSS 13.0 software. Aberration data between the anterior cornea and posterior cornea was compared by a Mann- Whitney test. Spearman analysis was used to show the relationship between Zernike terms and related factors. Results The mean Zernike aberrations for the cornea tended to become progressively smaller as the order increased. Other higher-order coefficients were close to zero except for third-order and fourth-order aberrations. The posterior corneal RMS errors were much smaller than the anterior surface, and the anterior corneal RMS was compensated by the posterior cornea. Intraocular pressure （IOP） had a statistically significant relationship to RMS for 3^rd-order and 6^th-order aberrations of the anterior cornea, 5^th-order and 6^th-order aberrations of the posterior cornea, and 3^rd-order and 6^th order aberrations of the entire cornea （r=0.217, 0.248, 0.269, 0.210, 0.222, 0.282; P〈0.05）. There was no statistically significant relationship between the thinnest corneal thickness and Zernike aberrations and there was no statistically significant difference in the higher-order aberration RMS values between males and females. Zernike terms were relatively symmetrical between right and left eyes. Conclusion Mean Zernike aberrations for the cornea in myopia tended to become progressively smaller with increasing order. The posterior corneal RMS errors were much smaller than for the anterior surface. The entire corneal RMS involved compensation of the anterior and by the posterior corneas. For higher-order aberrations, there were no significant differences between the left and right eyes; there was also no significant difference between genders.