推导出新的角膜屈光力公式, 并以此探讨由近视眼准分子激光角膜原位磨镶术( laser in situ keratomileusis, LASIK) 引起的角膜屈光力变化. 收集 710 只近视眼( 362 例)LASIK 术前、 术后数据, 获
得本组近视眼 LASIK 术后角膜曲率增量(ΔS IM K ) 与眼总屈光力增量( ΔD) 的回归方程: ΔD = 1.209 ΔS IM K - 0  265 ( r= 0  979, P= 0  000) . 由角膜屈光率得出: 正常角膜前表面屈光分力 F 1 = K /[ 1- ( n 2
- n 3 )/ (n 3 - n 1 )] ; 后表面屈光分力 F 2 = K/[ 1- ( n 3 - n 1 ) /( n 2 - n 3 )] . 结合上述回归方程和角膜前表面屈光分力的关系式可以得出近视眼 LASIK 术后 ΔD= 1 ?065 ΔF- 0 ? 265. 结论: LASIK 术后的角膜总屈
光力: F L = 1.135 14K L - 0  13514 K; 近视眼 LASIK 术后的角膜总屈光力增量( ΔF) 与眼总屈光力增量( ΔD)基本一致; LASIK 术后, 常规角膜曲率测量仪测出的仅为角膜前表面曲率, 不能代表整体的角膜
曲率; 近视眼 LASIK 术后的角膜总屈光力小于角膜曲率测量值; 该角膜屈光力公式计算过程简单、 结果可靠, 具有实用价值.

 We obtained a new formula of corneal refractive power and using it to investigate the variations of corneal refractive powers after laser in situ keratomileusis ( LASIK) , thus providing a theoretical basis for calculation of
corneal refractive powers. 362 cases ( 710 eyes) of myopia patients who had undergone LASIK were involved in this study. We established a regression equation of the variations of corneal curvature (S IM K ) and the variations of eye
diopter Δ D), Δ D = 1 209K - 0?265 ( r = 0.978, P= 0 .000) . From the new corneal refractive power formula refractive power of the anterior corneal surface F 1 = K/[ 1- ( n 2 - n 3 ) /( n 3 - n 1 ) ] and refractive power of the
posterior corneal surface F 2 = K/ [1- ( n 3 - n 1 /( n 2 - n 3 ) ] were derived. Based on the regression equation and the equation of corneal anterior surface power, we got the relationship between ? D and ? F for myopia eyes after
LASIK: ΔD= 1?065 F- 0?265. We concluded: the corneal refractive power after LASIK: F L = 1 .135 14K L - 0.135 14K ; there is a similarity between ΔD and Δ F for myopia patients who have undergone LASIK; after
LASIK, the corneal curvature measured by keratometer is K of the anterior corneal surface only and it cannot represent the whole corneal curvature; after LASIK, the corneal refractive power is less then the corneal curvature
measured by keratometer in myopia eyes; the new formula has the advantages of handy calculation, reliable and be of practical value.