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目的探讨准分子激光原位角膜磨镶术(LASIK)后角膜后表面的改变的特点和影响因素。方法对61例行LASIK术的近视患者分别于术前、术后1周、1个月、3个月采用OrbscanⅡ观察角膜后表面的曲率半径、不规则系数、前房深度,并利用多元回归分析术后1周角膜后表面的前膨与影响因素的关系,以最佳适合球面(PBFS)曲率半径的差值和角膜后表面高度差(PED)作为角膜后表面的前膨的指标。结果LASIK术前、术后1周、1个月、3个月前房深度分别为(3.2448±0.2806)、(3.2770±0.2810)、(3.2579±0.2932)、(3.2651±0.2875)mm;PBFS曲率半径分别为(6.5095±0.2177)、(6.3731±0.2127)、(6.4257±0.2358)、(6.4354±0.2266)mm;角膜后表面5.0mm范围的不规则系数分别为0.622±0.142、0.978±0.244、0.884±0.207、0.881±0.174,术后各期较术前明显增大(P<0.01),术后1个月和3个月的差异无统计学意义(P>0.05)。多元回归分析显示术后1周角膜后表面的前膨与术前屈光度数呈正相关(r=0.0173,P=0.005),与术后1周角膜厚度呈负相关(r=-1.495,P=0.001)。结论LASIK矫正近视直接改变了角膜前表面,也相应引起了角膜后表面的变化,术后角膜后表面变陡且不规则性增加,但3个月内不会渐进性发展。其改变与术前屈光度数呈正相关,与术后1周角膜厚度呈负相关。
Objective To investigate the characteristics and influential factors of corneal posterior surface changes after laser in situ keratomileusis (LASIK). Methods Sixty-one patients with myopia underwent LASIK were treated with Orbscan Ⅱ for 1 week, 1 month, 3 months after surgery to observe the curvature radius, irregularity coefficient and anterior chamber depth of the corneal surface. Multiple regression analysis The anterior swelling of the posterior corneal surface at 1 week after surgery was related to the influencing factors. The difference of the radius of curvature of best fit spherical surface (PBFS) and the posterior corneal height difference (PED) were used as an index of anterior corneal swelling. Results The preoperative, postoperative 1 week, 1 month, and 3 month preoperative depth were 3.2448 ± 0.2806, 3.2770 ± 0.2810, 3.2579 ± 0.2932 and 3.2651 ± 0.2875 mm, respectively. PBFS radius of curvature (6.5095 ± 0.2177), (6.3731 ± 0.2127), (6.4257 ± 0.2358) and (6.4354 ± 0.2266) mm, respectively. The irregularities in the range of 5.0 mm at the posterior corneal surface were 0.622 ± 0.142, 0.978 ± 0.244 and 0.884 ± 0.207 , 0.881 ± 0.174 respectively. There was no significant difference between one month and three months after operation (P> 0.05). Multiple regression analysis showed that the anterior corneal anteversion was positively correlated with preoperative refractive power (r = 0.0173, P = 0.005) at 1 week after operation and negatively correlated with corneal thickness at 1 week after operation (r = -1.495, P = 0.001 ). Conclusion LASIK correction of myopia directly changes the anterior surface of the cornea, which in turn causes the corneal posterior surface to change. The posterior corneal surface becomes steeper and the irregularity increases. However, it does not progress gradually within 3 months. The change was positively correlated with preoperative refractive power and negatively correlated with corneal thickness at 1 week after operation.