PURPOSE To evaluate the impact of cap thickness for small incision lenticule extraction (SMILE) on changes in corneal curvature and biomechanics. METHODS One hundred eyes (50 patients) were enrolled in this prospective contralateral eye study. The difference in manifest refraction spherical equivalent (MRSE) in the same patient was less than 0.50 diopters. SMILE was performed with a randomized cap thickness of 110 µm in one eye and 140 µm in the other eye. MRSE, uncorrected distance visual acuity (UDVA), and corneal curvature and biomechanics were evaluated. The anterior and posterior surfaces of the corneal curvature (mean keratometry [Km] values 2, 4, and 6 mm from the pupil center) were measured by Pentacam HR (Oculus Optikgeräte, Wetzlar, Germany) and changes in corneal biomechanics at 6 months postoperatively by Scheimpflug technology. RESULTS There was no significant between-group difference in UDVA or MRSE postoperatively. Postoperative changes in Km at the anterior surface (ΔKm-ant) in the 4-mm zone were significantly higher in the 110-µm group than in the 140-µm group at 1 day and 1, 3, and 6 months postoperatively (P = .043, .045, .003, and .049, respectively); at 3 months, the ΔKm-ant in the 6-mm zone was higher in the 110-µm group (P = .035). The changes in second appla-nation time, deformation amplitude, and integrated radius were significantly less in the 110-µm group (P = .031, .049, and < .001, respectively). CONCLUSIONS A thicker corneal cap caused less change in anterior surface curvature after SMILE for moderate or low myopia, with no significant difference in UDVA and MRSE. [J Refract Surg. 2020;36(2):82-88.].

中文翻译：

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帽厚度对SMILE后角膜曲率和角膜生物力学的影响：一项对侧眼前瞻性研究。

目的评估小切口小孔摘除术（SMILE）的帽厚度对角膜曲率和生物力学变化的影响。方法这项前瞻性对侧眼研究纳入了一百只眼（50例患者）。同一患者的明显屈光度当量（MRSE）差异小于0.50屈光度。SMILE的一只眼睛随机盖厚度为110 µm，另一只眼睛随机盖厚度为140 µm。评估了MRSE，未矫正的远视力（UDVA）以及角膜曲率和生物力学。用Pentacam HR（德国Wetzlar的OculusOptikgeräte）测量角膜曲率的前后表面（距瞳孔中心2、4和6mm的平均角膜曲率[Km]值），并在术后6个月测量角膜生物力学的变化。由Scheimpflug技术提供。结果术后UDVA或MRSE组间无显着差异。术后1天，1、3和6个月，在110 µm组中，术后4 mm前表面Km的变化（ΔKm-ant）明显高于140 µm组（P = .043，.045，.003和.049）；在3个月时，在110微米组中6毫米区域的ΔKm蚂蚁更高（P = .035）。110 µm组的第二施加时间，变形幅度和积分半径的变化明显较小（分别为P = .031，.049和<.001）。结论中度或低度近视SMILE后较厚的角膜帽引起的前曲面曲率变化较小，UDVA和MRSE差异无统计学意义。[J Refract Surg。2020; 36（2）：82-88。]。