近视眼眼轴及角膜表面形态的测定分析

Detection and analysis of ocular anteriorposterior axis and corneal surface shapes with myopia

目的分析近视眼眼轴和角膜表面形态改变的相互关系。方法175例327眼近视，分为低中度、高度和超高度3组，用眼科A／B超仪测量每只眼轴长；用角膜地形图仪检测角膜表面形态，所测数据作组间及相互间比较，统计学分析。结果327眼平均眼轴长为26．46±1.71mm，低中度组为25.08±0.94mm，高度组为26.06±0.83mm，超高度组为28.02±1．50mm，组间差异有显著性意义（P＜0.01）；角膜表面规则性系数（SRI）值为0．28±0．27，角膜表面非对称性系数（SAI）值为0．96±0．53，平均角膜屈光力（ACP）值为43.91±1．42D，角膜表面散光（CYL）值为1．92±0．90D，其中CYL值组间差异有显著性意义，其余各参数组间无显著性差异（P＞0.05）。眼轴值与CYL值呈正相关。结论近视眼眼轴较正视眼眼轴长，随着近视屈光度的增大，角膜非对称性加大，角膜散光也增大，而角膜屈光力无明显改变。近视眼眼轴变长是屈光度增加的主要原因，比角膜屈光力的改变更具决定意义。

Objective To investigate the correlation of ocular anteriorposterior axis in myopia with the change of corneal surface shapes.Methods 327 eyes (175 patients)of myopia were divided into moderate, high and severe myopia groups, were examined the ocular anteriorposterior axis with A/B ultrasonography and comeal surface shapes with corneal topography. The data were correlated and compared with that of different groups.Results The average ocular anteriorposterior axis in 327 myopia were 26. 46±1. 71mm, the moderate myopia group 25.08±0. 94mm. the high myopia 26. 06±0. 83mm and the severe myopia 28. 02±1. 50mm. There were significant differences among these 3 groups (P<0.01).The comeal surface regular indexes (SRI)in myopia were 0. 28±0. 27, the corneal surface asymmetry indexes (SAI)were 0. 96±0. 53, the average comeal powers (ACP ) were 43. 91±1. 42D, corneal surface cylinder (CYL ) were 1.92±0. 90D. There were significant differences among the data of CYL,but no among other data in myopia group. The ocular anteriorposterior axis had positive correlation with CYL.Conclusion The ocular anteriorposterior axises of myopia were longer than that of normal eyes. The more severe the myopia, the more asymmetry of cornea and the more severe the astigmatism, but there had no change of comeal refractive powers. The elongation of the ocular an teriorposterior axis was the main cause of the development of myopia and had more significant difference than the changes of corneal refractive powers.