飞秒激光小切口角膜基质透镜取出术对角膜前后表面非球面性的影响

目的研究飞秒激光小切口角膜基质透镜取出术(small incision lenticule extraction,SMILE)对角膜前后表面不同直径范围内非球面参数(Q值)的影响。方法选择行SMILE治疗并定期随访3个月以上的近视患者81例81眼,使用Pentacam眼前节分析系统对患者术前和术后3个月角膜前后表面6 mm、7 mm、8 mm和9 mm直径范围的Q值进行测量,分析手术前后角膜前后表面Q值的变化规律,并对相关影响因素采用Pearson相关分析。结果 SMILE术前角膜前表面6 mm、7 mm、8 mm、9 mm直径范围内Q值分别为-0.29±0.11、-0.33±0.11、-0.35±0.11和-0.38±0.11,术后3个月分别为0.47±0.34、0.51±0.33、0.50±0.31和0.43±0.28,进行配对t检验,其差异均有统计学意义(t=-22.51、-24.75、-26.47、-27.49,均为P<0.05)。Pearson相关分析发现:手术前后角膜前表面曲率变化与角膜前表面△Q值呈正相关(r=0.89,P<0.05)。SMILE术前角膜后表面6 mm、7 mm、8 mm、9 mm直径范围内Q值分别为-0.12±0.18、-0.21±0.17、-0.29±0.16和-0.38±0.14,术后3个月分别为-0.07±0.18、-0.16±0.16、-0.24±0.15和-0.35±0.13,其差异均有统计学意义(t=-3.45、-5.11、-5.14、-3.51,均为P<0.05)。Pearson相关分析发现:手术前后角膜后表面曲率变化与角膜后表面△Q值呈正相关(r=0.56,P<0.05)。结论 SMILE手术改变了角膜前后表面的非球面特性,术后Q值均向正值方向变化。

Effect of small incision lenticule extraction on anterior and posterior corneal asphericity

Objective　To investigate the effect of small incision lenticule extraction（SMILE） on anterior and posterior corneal asphericity （Q-value）.Methods　Eighty one eyes of 81 patients were included in this study.All the patients accepted the surgery of SMILE and completed 3 months follow-up.The Q-values of the anterior and posterior corneal surface for different corneal diameters （6 mm，7 mm，8 mm and 9 mm） were measured with Pentacam before and 3 months after operation，and the changes in the Q-values and the factors were analyzed by Pearson.Results　The Q-values of the anterior corneal surface from diameters of 6 mm，7 mm，8 mm and 9 mm were -0.29±0.11，-0.33±0.11，-0.35±0.11 and -0.38±0.11，respectively；3 months after operation，the values were 0.47±0.34，0.51±0.33，0.50±0.31 and 0.43±0.28，respectively，and the differences were statistically significant by paired-samples t test （t=-22.51，-24.75，-26.47，-27.49，all P<0.05）.Pearson correlation analysis found a positive correlation between the changes of corneal anterior Q-values and the changes of anterior corneal curvature（r=0.89，P<0.05）.The Q-values of the posterior corneal surface from diameters of 6 mm，7 mm，8 mm and 9 mm were -0.12±0.18，-0.21±0.17，-0.29±0.16 and -0.38±0.14；3 months after operation，the values were -0.07±0.18，-0.16±0.16，-0.24±0.15 and -0.35±0.13，respectively，and there were all significant differences between them （t=-3.45，-5.11，-5.14，-3.51，all P<0.05）.Pearson correlation analysis found a positive correlation between the changes of corneal posterior Q-values and the changes of posterior corneal curvature（r=0.56，P<0.05）.Conclusion　SMILE causes significant changes on the anterior and posterior corneal asphericity.The Q-values increased to positive values after SMILE surgery.