放射状角膜切开合并横切口的地形图及屈光的改变

Changes of corneal topography and refraction after radial keratotomy and its combination with transverse incision

目的了解放射状角膜切开术（ｒａｄｉａｌｋｅｒａｔｏｔｏｍｙ，ＲＫ）联合横切口手术及ＲＫ前后角膜形态、屈光力的改变及横切口的愈合状况。方法应用计算机辅助角膜地形图检测仪对ＲＫ联合横切口手术及ＲＫ进行测定，并对其角膜强弱轴屈光力及角膜横切口的愈合进行分析。结果角膜表面规则指数和角膜表面不规则指数随近视散光的增加而增大，角膜视区３、５、７ｍｍ屈光度越向中心下降越明显，ＲＫ联合横切口强轴屈光度下降明显高于ＲＫ，弱轴屈光度下降与ＲＫ比差异无显著性。动物试验显示横切口愈合。结论近视散光越大角膜表面不规则指数、角膜表面规则指数可随之增大，两种手术的角膜形态由术前的正性非球面形变为术后的负性非球面形，手术切口使屈率半径加大、屈光力下降，越接近视区越明显，而刀数越多以上变化则越大。在强子午线上增加一对短的横切口，不但能使强子午线上的屈光力下降，且还不影响近视球镜的下降，对角膜的规则性、对称性无明显影响。动物试验表明一对短的横切口不引起伤口的迟缓愈合。

Objective In order to understand the changes of morphology and refractive power of cornea after radial keratotomy (RK) and its combination with transverse incision (Tincision), and the wound healing of the Tincision. Methods Corneal topography aided with a computer was used to analyze the changes of patients having undergone RK and RK combined with Tincision. The wound healing was analyzed, and the refractive powers of strong axis and weak axis of corneas were measured. Results Corneal surface regularity index (SRI) and surface asymmetry index (SAI) became greater and greater along with the increase of myopiaastigmatism. The refractive powers of corneal visual area 3,5,7 mm decreased when getting closer to the center of the cornea. The refractive power of the strong axis in cornea with RK combined with Tincision obviously decreased more than that of RK. There was no such difference at weak axis between RK and RK combined with Tincision. Conclusions Corneal SAI and SRI will increase when myopiaastigmatism increases. The morphologic changes are from positive nonspherical lens before surgery to negative nonspherical lens after surgery. The increase of radius of curvature and the decrease of refractive power are due to incisions. These phenomena become clearer when the incision getting closer to the visual area or more incisions are performed. A Tincision less than 2 mm long along the strong axis of astigmatism not only can lessen refractive power of strong axis, but also can not affect RK results. This kind of Tincision does not delay the wound healing either.