SMILE与FS—LASIK对近视眼角膜基质切削深度可预测性的比较

Comparison of corneal ablation depth predictability between small incision lenticule extraction and femtosecond laser-assisted in situ keratomileusis for myopia

背景全飞秒激光小切口角膜基质透镜取出术（SMILE）已越来越多地用于近视的矫治，其手术的安全性、可预测性也受到关注。目的分析和比较SMILE与飞秒激光角膜原位磨镶术（FS—LASIK）对中央角膜组织切削深度的可预测性。方法采用非随机对照研究方法，选取于2015年10月至2016年5月在北京同仁医院拟行角膜屈光手术的近视患者135例270眼，根据患者的选择分为SMILE组69例138眼和Fs—LASIK组66例132眼，组间患者人口基线特征匹配，分别接受SMILE和FS．LASIK，分别于术前及术后1周采用RTVueFD—OCT测量术眼中央角膜厚度值，观察指标包括术中角膜实际切削深度、切削误差和术眼术后屈光度变化，术前与术后1周中央角膜厚度的差值为实际切削深度，预测切削深度与实际切削深度间的偏差值为切削误差，比较2个组间各项测量指标的差异，探讨预测切削深度与实际切削深度值之间的关系。结果SMILE组和FS—LASIK组术眼术后球镜度、柱镜度及等效球镜度的差异均无统计学意义（t=－1．826、－1．405、－1．420，均P〉0．05）。SMILE组患者术后角膜实际切削深度为（76．96±15．27）μm，低于预测切削深度的（96．76±16．52）μm，差异有统计学意义（t=－23．016，P〈0．01）；FS—LASIK组术眼实际切削深度与预测切削深度分别为（77．92±18．69）μm和（77．42±15．60）μm，差异无统计学意义（t=－0．604，P=0．547）。SMILE组术后切削误差量平均为（20．55±8．51）μm，大于FS—LASIK的（7．17±5．97）μm，组问差异有统计学意义（t=14．950，P〈0．01）。2个组术眼角膜预测切削深度与实际切削深度值问均呈线性正相关（r=0．799、0．867，均P〈0．01），SMILE组与FS—LASIK组术眼实际切削深度均随着预测切削深度的增加而增加，直线回归方程分别为l，：3．892±0．749X和Y=3．443±0．957X。结论SMILE术中实际切削深度低于预测切削深度，而FS—LASIK术中2者无明显差异，FS—LASIK可预测性好于SMILE。

Background Recently,small incision lenticule extraction （SMILE） procedure is used to correct myopia. The clinical safety and efficiency of SMILE have been approved, but its predictability to corneal ablation depth is brought into focus. Objective This study was to compare the predictability of ablation depth in central cornea between SMILE and femtoseeond laser-assisted in situ keratomileusis （FS-LASIK） for myopia. Methods A non- randomized controlled clinical study was performed. Two hundred and seventy eyes of 135 myopic patients who were going to receive corneal refractive surgery were included in Beijing Tongren Hospital from October 2015 to May 2016. SMILE and FS-LASIK were performed on 138 eyes of 69 patients and 132 eyes of 66 patients matched in demography respeetively under the informed consent. Central corneal thickness was measured by RTVne FD-OCT before and 1 week after surgery. The refractive power, actual ablation depth （ difference of central corneal thickness before and after surgery） and central corneal cutting error （difference between theoretically expected ablation depth and real ablation depth） were intergrouply compared, and the correlation of real ablation depth with theoretically expected ablation depth was assessed. Results No significant difference was found in spherical power, astigmatic power and spherical equivalent after surgery between SMILE group and FS-LASIK group （ t = - 1. 826, - 1. 405, - 1. 420, all at P〉0.05 ）. The actual ablation depth was （ 76.96 ± 15.27 ） μm in the SMILE group, which was significant lower than （96.76± 16.52 ） μm of theoretically expected ablation depth （ t = - 23. 016, P 〈 0.01 ） ; however, there was no significant difference in the FS-LASIK group between actual and expected ablation depth （ [ 77.92± 18.69 ] μm versus [77.42±15.60] μm） （t=-0.604,P=0.547）.The central corneal cutting error was （20.55±8.51）μm in the SMILE group and （7. 17 ± 5.97 ） μm in the FS-LASIK group, showing a significant difference between them （t= 14. 950,P〈0.01 ）. The positive linear correlations were seen between actual and expected ablation depth in both SMILE group and FS-LASIK group （r = 0. 799,0. 867, both at P〈0.01 ）. The actual ablation depth was increased over expected ablation depth, with the regression equations of Y = 3. 892 ± 0. 749X in the SMILE group and Y = 3. 443 ± 0. 957X in the FS-LASIK group. Conclusions The actual corneal ablation depth is less than expected corneal ablation depth in SMILE procedure, while in FS-LASIK procedure, the actual corneal ablation depth appears to be consistent with the expected one,inferring a good predictability in corneal ablation depth in FS-LASIK surgery.