飞秒激光小切口角膜基质透镜取出术后角膜后表面高度变化及其影响因素的研究

An analysis of changes in posterior corneal elevation and relevant factors after small incision lenticule extraction

目的探讨飞秒激光小切口角膜基质透镜取出术（SMILE）后角膜后表面高度的变化及可能影响因素。方法回顾性系列病例研究。对44例（83只眼）近视眼患者施行SMILE，于术前、术后1d及术后1、3、6个月进行Pentacam眼前节分析系统检查，分别测量角膜顶点及以顶点为圆心2和6mm直径上0°、45°、90°、135°、180°、225°、270°、325°各8个点，总共17个点的角膜后表面高度变化。统计学比较采用配对t检验和Person相关分析。结果术后1d及1、3、6个月，角膜顶点后表面高度与术前相比变化分别为（-1．72±2．59）、（-0．98±2．37）、（-0．45±1．81）、（-0．25±2．20）μm，除术后6个月外，其余差异均有统计学意义（t=-6．07，-3．75，-2．24；P〈0．05）。2mm环后表面高度变化分别为（-1．42±2．06）、（-0．69±1．86）、（-0．30±1．50）、（-0．22±1．58）μm，术后1d和1个月差异有统计学意义（t=-6．28，-3．38；P〈0．05）。6mm环后表面高度变化分别为（1．48±1．47）、（0．98±1．32）、（0．90±1．31）、（0．90±1．16）μm，差异均有统计学意义（t=9．17，6．77，6．29，5．74；P〈0．05）。术后1个月与术后1d相比顶点、2mm环、6mm环均明显向术前位置恢复，分别为（0．75±2．55）、（0．73±1．97）、（-0．50±1．60）μm。术后3个月与1个月相比顶点及2mm环角膜仍向术前恢复，分别为（0．53±2．22）、（0．39±1．80）Hm，6mm环无明显变化。术后6个月与3个月相比无明显差异。SMILE术后角膜后表面高度变化与术前等效球镜度数、术前眼压、平均手术切削深度、平均剩余角膜基质床厚度、角膜滞后量、角膜阻力因子无相关性。结论SMILE术后角膜周边轻度前移，中央先后移然后逐渐恢复。SMILE术后角膜后表面高度变化与术前等效球镜、术前眼压、平均手术切削深度、平均剩余角膜基质床厚度、角膜滞后量、角膜阻力因子无相关性。

Objective To investigate changes in posterior corneal elevation after small incision lenticule extraction （SMILE） and related factors. Methods Retrospective case series study. Eighty-three eyes of 44 myopic patients undergoing SMILE were examined with the Pentacam preoperatively, and at 1 day, 1 month, 3 months, and 6 months postoperatively. Posterior corneal elevation at the corneal apex and 0°, 45°, 90°, 135°, 180°, 225°, 270° and 325° points of the 2 mm and 6 mm diameter （total, 17 points） was analyzed. Results The changes in posterior corneal elevation at I day, 1 month, 3 months, and 6 months were （ - 1.72±2.59）, （-0.98±2.37）, （ -0.45± 1.81 ） and （-0.25±2.20） μm, respectively, at the corneal apex. The results were statistically significant （t=6.07, 3.75, 6.07; P〈0.05）, except 6 months. The changes in posterior corneal elevation were （ - 1.42±2.06）, （ -0.69± 1.86）, （ -0.30± 1.50） and （ -0.22± 1.58 ）μm, respectively, in the 2 mm circle. The results of 1 day and 1 month were statistically significant （t=6.28, 6.28, P〈0.05）. The changes in posterior corneal elevation were （ 1.48± 1.47）, （0.98± 1.32）, （0.90± 1.31 ） and （0,90±1.16）μm, respectively, in the 6 mm circle .The results were totally statistically significant （t=6.28, 6.28, P〈0.05）. There were statistically significant differences between 1 month and 1 day postoperatively in the corneal apex, 2 mm and 6 mm circles. The changes were （0.75±2.55）, （0.73 ±1.97） and （-0.50± 1.60）μm. There were statistically significant differences between 3 months and 1 month postoperatively in the corneal apex and 2 mm circle. The changes were （0.53±2.22） and （0.39 ± 1.80） μm. No significant change was found in the 6 mm circle. Between postoperative 6 months and 3 months, there were no statistically significant differences. The spherical equivalent, intraocular pressure, ablation depth, residual bed thickness, corneal hysteresis, and corneal resistance factor had no obvious correlation with the changes in posterior corneal elevation. Conclusions After SMILE, the surrounding cornea was slightly forward, while the central posterior cornea was slightly backwards, and returned gradually. The spherical equivalent, intraocular pressure, ablation depth, residual bed thickness, corneal hysteresis, and corneal resistance factor had no obvious correlation with the changes in posterior corneal elevation.