PURPOSE To evaluate corneal stiffening in porcine eyes induced by corneal cross-linking (CXL) using riboflavin dissolved in either aqueous dextran or hydroxypropyl methylcellulose (HPMC) solution. METHODS Fifty-one porcine corneas were divided into three groups of 17 each. After deepithelialization, the first (Dresden) group was treated for 30 minutes with 0.1% riboflavin (riboflavin-5-monophosphate in 0.9% NaCl) dissolved in hypertonic 20% dextran and the second (HPMC) group for 30 minutes with isotonic solution containing 0.1% riboflavin and 1.1% HPMC. Thereafter, corneas of both groups were irradiated using 5.4 J/cm2 (irradiance of 9 mW/cm2 for 10 minutes; 10*9). After CXL, all corneas were kept in an isotonic 16% dextran bath for 2 hours to obtain an equal hydration state. The third group served as the control group. Stress-strain measurements were performed on 5-mm-wide strips. Corneal thickness was monitored throughout the entire course of the experiments. RESULTS The required stress for a 10% strain was increased by 83% in the Dresden group and 35% in the HPMC group compared to the control group. Resultant Young's modulus (at 10% strain) was 2.53 ± 0.73, 1.87 ± 0.50, and 1.47 ± 0.44 Pa for the Dresden, HPMC, and control groups, respectively. The differences between the Dresden and HPMC groups (P = .006), the Dresden and control groups (P < .001), and the HPMC and control groups (P = .014) were statistically significant. Pachymetry measurements showed a significantly increased corneal thickness after application of HPMC compared with the Dresden group (P = .002) and control group (P = .041). CONCLUSIONS The biomechanical stiffening of the cornea by CXL can be achieved using dextran- and HPMC-based riboflavin solutions in porcine corneas with an application time of 30 minutes. Dextran-based riboflavin solutions seem to induce a slightly stronger biomechanical response in this setting. HPMC solutions induce less thinning than dextran solutions. [J Refract Surg. 2021;37(9):631-635.].

中文翻译：

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角膜与溶解在葡聚糖溶液中的核黄素与羟丙基甲基纤维素交联后的生物力学响应。

目的 评估使用溶解在葡聚糖水溶液或羟丙基甲基纤维素 (HPMC) 溶液中的核黄素进行角膜交联 (CXL) 引起的猪眼角膜变硬。方法将51只猪角膜分为3组，每组17只。去上皮后，第一组（德累斯顿）用溶解在高渗 20% 葡聚糖中的 0.1% 核黄素（核黄素 5-一磷酸在 0.9% NaCl 中）处理 30 分钟，第二组（HPMC）用含有 0.1 的等渗溶液处理 30 分钟。 % 核黄素和 1.1% HPMC。此后，两组的角膜均使用 5.4 J/cm2（9 mW/cm2 的辐照度，持续 10 分钟；10*9）进行照射。CXL 后，所有角膜都在等渗 16% 葡聚糖浴中保持 2 小时，以获得相等的水合状态。第三组作为对照组。应力应变测量是在 5 毫米宽的条带上进行的。在整个实验过程中监测角膜厚度。结果 与对照组相比，Dresden 组和 HPMC 组中 10% 应变所需的应力增加了 83% 和 35%。对于德累斯顿、HPMC 和对照组，所得杨氏模量（在 10% 应变下）分别为 2.53 ± 0.73、1.87 ± 0.50 和 1.47 ± 0.44 Pa。德累斯顿和 HPMC 组 (P = .006)、德累斯顿和对照组 (P < .001) 以及 HPMC 和对照组 (P = .014) 之间的差异具有统计学意义。与德累斯顿组 (P = .002) 和对照组 (P = .041) 相比，厚度测量显示应用 HPMC 后角膜厚度显着增加。结论 在猪角膜中使用基于葡聚糖和 HPMC 的核黄素溶液，应用时间为 30 分钟，可以实现 CXL 对角膜的生物力学硬化。在这种情况下，基于葡聚糖的核黄素溶液似乎会引起稍强的生物力学反应。HPMC 溶液引起的稀释比葡聚糖溶液少。[J 屈光手术。2021;37(9):631-635.]。