目的：评估不同程度近视患者SMILE术前预估角膜切削厚度与术后实际角膜切削厚度的差异，探究SMILE术中角膜基质切削厚度的精确性。

方法：前瞻性研究。收集2017-01/2019-08在我院行SMILE手术的近视患者143例234眼，根据术前等效球镜度分为低(-0.50～-3.00D，78眼)、中(>-3.00～-6.00D，78眼)、高(>-6.00D，78眼)度近视组，观察三组患者手术前后视力和等效球镜度，并分别于术前和术后1mo采用Pentacam眼前节综合分析系统测量中央角膜厚度，比较术前预估角膜切削厚度与术后1mo实际切削厚度的差异，探讨SMILE术中不同屈光状态角膜基质切削厚度的精确性。

结果：术后1mo，所有患眼裸眼视力均达0.8以上，98.3%患眼裸眼视力达1.0以上。所有患者术后1mo角膜平均实际切削厚度低于平均预估切削厚度(84.92±23.15μm vs 100.07±26.83μm，P<0.01)，平均切削差异值为15.15±10.34μm。低、中、高度近视组患者角膜实际切削厚度均低于各组预估角膜切削厚度(P<0.01)，切削差异值分别为8.81±7.78、15.59±9.27、21.05±10.03μm。术前，本研究纳入患者平均等效球镜度为-4.85±2.15D，术前等效球镜度与切削差异值之间具有直线回归关系(Y=-2.2495X+3.9287，R²=0.1589)，等效球镜度数越大，切削差异值越大(t=-6.620，P<0.001)。

结论：SMILE手术的角膜基质实际切削厚度低于预估切削厚度，且近视度数越高，切削差异越大，但术后屈光矫正效果理想，术中角膜切削厚度的差异并不影响屈光矫正手术的精确性。

METHODS: This prospective study included 234 eyes(143 myopic patients), who had undergone SMILE in our hospital from January 2017 to August 2019. The patients were divided into three groups according to a manifest refraction spherical equivalent(MRSE): low myopia(-0.50 to -3.00D, 78 eyes), moderate myopia(>-3.00 to -6.00D, 78 eyes), and high myopia(>-6.00D, 78 eyes). Observe the uncorrected distance visual acuity(UDVA)and MRSE before and after operation. The central corneal thickness(CCT)was measured by Pentacam preoperatively and postoperatively at 1mo. Compare the discrepancy between estimated corneal ablation thickness and measured corneal ablation thickness of three groups to discuss the precision of corneal ablation thickness in different refractive errors in SMILE.

RESULTS: The UDVA was 0.8 or better in all eyes and 1.0 or better in 98.3% eyes postoperatively. The average measured corneal ablation thickness was significantly lower than average estimated corneal ablation thickness(84.92±23.15μm vs 100.07±26.83μm, P<0.01). The average cutting error was 15.15±10.34μm. The measured corneal ablation thickness of low myopia, moderate myopia and high myopia was significantly lower than the estimated corneal ablation thickness, respectively(P<0.01). The cutting error of low myopia, moderate myopia and high myopia was 8.81±7.78, 15.59±9.27, 21.05±10.03μm respectively. The average MRSE of all patients was -4.85±2.15D preoperation, there was a linear regression relation between MRSE and cutting error(Y= -2.2495X+3.9287, R²=0.1589). The cutting error increased with MRSE(t=-6.620, P<0.001).

CONCLUSION: The measured corneal ablation thickness was lower than estimated corneal ablation thickness,the higher the refractive power was, the larger the cutting error would be in SMILE. Although there was significant discrepancy between measured corneal ablation thickness and estimated corneal ablation thickness, the effect of this surgery was ideal, the mismatch did not influence the precision of different refractive errors.