准分子激光屈光性角膜切削术后兔眼角膜后弹力层和内皮变化的比较研究

Changes in Descemet′s membrane and endothelium after photorefractive keratectomy in rabbits

目的 探讨去除角膜上皮对兔眼角膜内皮层和后弹力层的影响 ,并与准分子激光屈光性角膜切削手术 (photorefractivekeratectomy ,PRK)后兔眼角膜进行比较研究。方法 制作去除角膜上皮及PRK术后动物模型 ,以正常兔眼角膜做对照 ,分别于术后 2 4h、7d、14d及 30d时使用透射电子显微镜和扫描电子显微镜检测标本。结果 (1)去除角膜上皮兔眼的角膜内皮细胞线粒体明显增大 ,并出现纤维颗粒性电子致密带 ,该带在后弹力层中向前移行 ,这些改变与PRK术后兔眼角膜情况相似 ;(2 )去除角膜上皮兔眼的角膜内皮细胞水肿程度和病理变化过程与PRK术后兔眼角膜变化相似。结论 PRK术后兔眼角膜后弹力层出现纤维颗粒性电子致密物突起 。

Objective To investigate the effects of epithelial abrasion on the corneal endothelium and Descemet′s membrane and to compare the changes with those after eximer laser photoablation of the cornea. Methods The animal models of corneal epithelial abrasion and excimer laser photoablation of the cornea were performed on the rabbit eyes. The central epithelial abrasion, 7 mm in diameter, was created by mechanical removal of the epithelium, and the specimens were examined at 24 hours, 7 days, 14 days and 30 days by transmission and scanning electron microscopy. Corneas that were photoablated by an excimer laser and non treated normal corneas were investigated as controls. Results (1) Corneas with the epithelium removal showed massive enlargement of the mitochondria in the endothelium and exhibited a layer of electron dense fibrillogranular material that had migrated forward through the Descemet′s membrane. These alterations were similar to the changes observed after photoablation of the cornea by an excimer laser. (2) The edema and pathologic changes of corneal endothelium in eyes with denuded epithelium alone were similar to that observed after photoablation of the cornea by an excimer laser. Conclusion The extrusion of electron dense material in the Descemet′s membrane observed after excimer laser ablation destruction of the epithelial integrity.