J Refract Surg. 2020 Feb 1;36(2):82-88. doi: 10.3928/1081597X-20191216-01.
To evaluate the impact of cap thickness for small incision lenticule extraction (SMILE) on changes in corneal curvature and biomechanics.
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.
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).
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.].
评估小切口微透镜提取术（SMILE）中角膜帽厚度对角膜曲率和生物力学变化的影响。
本前瞻性对照眼研究纳入了 100 只眼（50 例患者）。同一患者的等效球镜（MRSE）差异小于 0.50 屈光度。在一只眼中进行 SMILE 手术，随机采用 110 µm 或 140 µm 的角膜帽厚度，另一只眼作为对照。评估 MRSE、未矫正远视力（UDVA）以及角膜曲率和生物力学。使用 Pentacam HR（德国韦茨拉尔的 Oculus Optikgeräte 公司）测量角膜前表面（从瞳孔中心 2、4 和 6 mm 处的平均角膜曲率[Km]值）和术后 6 个月的Scheimpflug 技术下的角膜生物力学变化。
术后两组间 UDVA 或 MRSE 均无显著差异。术后 1 天和 1、3、6 个月时，110 µm 组角膜前表面（4-mm 区）的 Km 变化（ΔKm-ant）明显高于 140 µm 组（P =.043、.045、.003 和.049）；3 个月时，110 µm 组的 6-mm 区的ΔKm-ant 更高（P =.035）。110 µm 组的二次压平时间、变形幅度和综合半径的变化明显更小（P =.031、.049 和 <.001）。
对于中低度近视，SMILE 术中采用较厚的角膜帽会导致角膜前表面曲率变化较小，而 UDVA 和 MRSE 无显著差异。
