PURPOSE To evaluate the biomechanical effect of corneal cross-linking (CXL) in paired human corneas following small incision lenticule extraction (SMILE) or photorefractive keratectomy (PRK) in an ex vivo model for postoperative ectasia. METHODS Twenty-six paired human corneas preserved in tissue culture medium were equally divided into two groups: right and left corneas were treated with PRK and SMILE, respectively. Corneal thickness was measured in all eyes before surgery. Corneas were stretched using an extensometer with two cycles of up to 9 N (570 kPA stress), followed by accelerated CXL with irradiance of 9 mW/cm2 for 10 minutes (fluence 5.4 J/cm2) in both groups. The elastic modulus was evaluated using two-dimensional stress-strain extensometry. RESULTS Following accelerated CXL, the ectatic cornea model showed a mean effective elastic modulus of 17.2 ± 5.3 MPa after PRK and 14.1 ± 5.0 MPa after SMILE. Although the elastic modulus in corneas previously subjected to PRK was higher, there was no significant biomechanical difference between the two groups (P = .093). CONCLUSIONS Under similar conditions, both experimental groups (PRK followed by CXL and SMILE followed by CXL) were characterized by similar biomechanical stability as measured experimentally on ex vivo human fellow corneas. The data suggest that, in the event of postoperative ectasia, the biomechanical improvement achieved by CXL may be similar after PRK and SMILE. [J Refract Surg. 2020;36(1):49-54].

中文翻译：

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SMILE和PRK在人角膜中的术后角化症的体内模型中具有类似的生物力学交联作用。

目的评估成角膜交联（CXL）在成对的人类角膜在小切口小孔镜摘除术（SMILE）或光折射角膜切除术（PRK）的体外模型中的生物力学效果。方法将保存在组织培养基中的26对成对的人角膜平均分为两组：分别用PRK和SMILE治疗左右角膜。在手术前测量所有眼睛的角膜厚度。使用引伸计拉伸角膜，两个循环的最大周期为9 N（570 kPA应力），然后在两组中以9 mW / cm2的辐照度加速CXL 10分钟（通量5.4 J / cm2）。弹性模量使用二维应力应变拉伸法进行评估。结果加速CXL后，直肠角膜模型显示PRK后平均有效弹性模量为17.2±5.3 MPa，SMILE后平均有效弹性模量为14.1±5.0 MPa。尽管先前接受PRK的角膜的弹性模量较高，但两组之间的生物力学差异不明显（P = .093）。结论在相似的条件下，两个实验组（PRK，然后是CXL，SMILE，然后是CXL）的特征是，在离体人类角膜上进行了实验测量，其生物力学稳定性相近。数据表明，在术后扩张期的情况下，PRK和SMILE后CXL实现的生物力学改善可能相似。[J Refract Surg。2020; 36（1）：49-54]。两组之间没有明显的生物力学差异（P = .093）。结论在相似的条件下，两个实验组（PRK，然后是CXL，SMILE，然后是CXL）的特征是，在离体人类角膜上进行了实验测量，其生物力学稳定性相近。数据表明，在术后扩张期的情况下，PRK和SMILE后CXL所实现的生物力学改善可能相似。[J Refract Surg。2020; 36（1）：49-54]。两组之间没有明显的生物力学差异（P = .093）。结论在相似的条件下，两个实验组（PRK，然后是CXL，SMILE，然后是CXL）的特征是，在离体人类角膜上进行了实验测量，其生物力学稳定性相近。数据表明，在术后扩张期的情况下，PRK和SMILE后CXL所实现的生物力学改善可能相似。[J Refract Surg。2020; 36（1）：49-54]。在PRK和SMILE之后，CXL实现的生物力学改善可能相似。[J Refract Surg。2020; 36（1）：49-54]。在PRK和SMILE之后，CXL实现的生物力学改善可能相似。[J Refract Surg。2020; 36（1）：49-54]。