角膜地形图和角膜曲率计测量散光的研究

目的探讨角膜地形图和角膜曲率计对屈光手术前、后角膜散光的应用价值。方法采用计算机辅助的角膜地形图、角膜曲率计及散瞳验光三种测量散光的方法,对屈光不正患者３６０只眼进行检查,同时对准分子激光角膜切削术（ｐｈｏｔｏｒｅｆｒａｃｔｉｖｅｋｅｒａｔｅｃｔｏｍｙ,ＰＲＫ）后７２只眼和准分子激光原位角膜磨镶术（ｅｘｃｉｍｅｒｌａｓｅｒｉｎｓｉｔｕｋｅｒａｔｏｍｉｌｅｕｓｉｓ,ＬＡＳＩＫ）后９５只眼的角膜散光用角膜地形图和角膜曲率计进行测量并比较。结果术前三组测量方法在散光轴位方面差异无显著性（Ｐ＞０．０５）。在散光度数上,角膜地形图△ＳｉｍＫ和角膜曲率计△Ｋ间差异无显著性（Ｐ＞０．０５）;而散瞳验光组与另两组间差异有显著性（Ｐ＜０．０１）。ＰＲＫ和ＬＡＳＩＫ术后△ＳｉｍＫ与△Ｋ值间差异有显著性（Ｐ＜０．０１）。结论角膜曲率计与角膜地形图对术前角膜散光测量具有相似的临床价值,角膜地形图图形与参数△ＳｉｍＫ值有关。但术后角膜地形图△ＳｉｍＫ测量的角膜散光较为准确

A research on clinical values of corneal topography and keratometer in measuring astigmatism

OBJECTIVE: To compare the accuracy of corneal topography, keratometer and cycloplegic retinoscopy in measuring astigmatism for refractive surgery. METHODS: Three hundred and sixty eyes with ametropia were randomly selected. The results of corneal topography, that of keratometer and cycloplegic retinoscopy in measuring astigmatism before refractive surgery were compared, and the measuring results of corneal topography and that of keratometer for 72 eyes after photorefractive keratectomy (PRK) and 95 eyes after laser in situ keratomileusis (LASIK) were also compared. RESULTS: No significant difference was found in axes of astigmatism among the three groups. As for diopters of astigmatism, there was no significant difference between the group of corneal topography (DeltaSim K) and the group of keratometer (DeltaK), but we found significant difference between the group of cycloplegic retinoscopy and the other two groups before and after refractive surgery. Significant difference was also found between DeltaSimK and DeltaK after PRK and LASIK. CONCLUSIONS: Our investigation demonstrates that before refractive surgery the keratometer has a similar clinical value as that of corneal topography, and the DeltaSim K value is related to the graphic pattern of corneal topography. However, keratometer is limited in measuring mild changes in corneal curvature after refractive surgery, while the astigmatism expressed by DeltaSim K in corneal topography is more accurate.