实验性高度近视眼巩膜胶原及弹性模量的变化

目的 探讨实验性高度近视眼巩膜组织的胶原及弹性模量的变化，进一步明确高度近视眼的发生机制。方法 1 月龄新西兰大白兔 20 只随机单侧眼球眼睑缝合建立高度近视眼动物模型，另一侧眼球为正常对照眼，建模 60 d 后，测量眼轴长度确定建模成功；获取不同部位巩膜组织（前部、赤道部和后部巩膜），一部分巩膜制成巩膜条带，用 Instron 5544 试验机检测巩膜的弹性模量，一部分巩膜组织固定后进行HE染色观察巩膜结构，一部分巩膜组织固定后通过电镜观察胶原原纤维，一部分巩膜组织匀浆检测羟脯氨酸浓度，确定胶原含量。结果 随着月龄增加，巩膜组织弹性模量和胶原含量不断增加，胶原原纤维的直径不断增大。高度近视眼后部巩膜的弹性模量、羟脯氨酸含量明显小于正常眼，且胶原原纤维的直径小于正常眼，而前部和中部巩膜未见明显差异。结论 在高度近视发生过程中，后部巩膜发生重塑，胶原原纤维的排布和胶原含量发生变化，导致后部巩膜生物力学性能降低，容易发生扩张和变形，进而引起近视。研究结果为后续以胶原为靶点，在生长发育早期防治高度近视眼奠定基础。
Objective To investigate changes in the collagen expression and elastic modulus in scleral tissues of experimental high myopia, so as to further explain the mechanism of high myopia. Methods Twenty one-month-old New Zealand white rabbits were monocularly treated by eyelid suturation randomly to build an experimental high myopia eye model. Eyes without such operation were set as the normal control. After 60 days, the experimental high myopia eye models were successfully established by measuring the eye axis. The eyeballs were obtained to assess three regions of the sclera (anterior, equatorial, and posterior area). The three regions of the scleral tissues were separately divided into four groups. The first group was made into scleral strips for elastic modulus measurement using an Instron5544. The second group was hematoxylin-and-eosin stained for observation of the scleral structures. The third group was used for electron microscopy to observe the size distribution of collagen fibrils. The last group was homogenized, and the concentration of hydroxyproline was measured to determine the collagen content. Results The elastic modulus, collagen content, and diameters of the collagen fibrils of each scleral region increased with age. The posterior sclera of high myopia had looser collagen fibril arrangement, less hydroxyproline concentration, and lower elastic modulus than the normal eyes. However, there was no significant difference as for the anterior and equatorial sclera. Conclusions The remodeled posterior sclera of high myopia has a looser collagen fibril arrangement, less collagen, and lower elastic modulus, which easily causes expansion and deformation and thus lead to high myopia. The research findings provide the theoretical guidance for high myopia prevention by targeting the collagen during early development.