光动力学角膜胶原交联对LASIK术后角膜瓣愈合影响的实验研究

Experimental LASIK Centre, study on the effect of corneal crosslinking for improving flap adhesion after

目的探讨核黄素-紫外线A诱导的角膜胶原交联对准分子激光原位角膜磨镶术（LASIK）术后角膜瓣与角膜基质床的黏附与愈合的作用。方法实验研究。健康成年新西兰白兔22只，随机依次编号，自身对照。建立兔LASIK动物模型，双眼行LASIK手术后，右眼给予核黄素一紫外线A胶原交联处理，左眼为空白对照。分别于术后1d、3d及1周随机取实验动物4只于裂隙灯下观察角膜透明性；术后1周、1个月及3个月，分别取实验兔4只做角膜组织病理切片，观察有无炎症细胞的浸润以及角膜各层细胞形态学变化。术后1个月，采用电子单纤维强力仪进行角膜瓣抗拉力检测，采用电子显微镜测量角膜组织胶原纤维直径。对抗拉力实验结果和胶原纤维直径分别采用独立样本t检验和配对t检验进行统计学分析。结果在给予核黄素点眼约20min之后，裂隙灯下可见前房内黄绿色条带，表明核黄素能够到达瓣下并穿透下方角膜基质层。术后裂隙灯观察显示，实验眼和对照眼的角膜透明性无明显差别。病理学结果显示，实验眼及对照眼均无明显的炎症细胞浸润，均可见“无细胞区”的存在，无明显差别。术后1个月，抗拉力实验结果显示，在不同的拉伸长度，实验眼角膜瓣与角膜基质床的黏附力较对照眼明显增强（P〈0．01）。电镜检查显示，实验眼角膜胶原纤维直径[（36．51±3．29）nm]大于对照眼[（29．55±1．74）nm]，差异有统计学意义（t=7．94，P〈0．01）。结论核黄素．紫外线A诱导的角膜胶原交联，在一定程度上能够促进角膜瓣与角膜基质床的黏着与愈合，并且不会引起明显的炎症反应。

Objective To investigate the effect of corneal crosslinking guided by riboflavin ultravilet rays on flap adhesion and healing in laser in situ keratomileusis （LASIK） in the rabbit. Methods LASIK flaps were created in 22 rabbit corneas in this experimental study. The right eyes were the experimental eyes while the left eyes were the control eyes. The edema and inflammation reaction of the corneas were observed with slit lamp at different time points （1 day, 3 days, 7 days after surgery）. Histopathological changes, including inflammatory cell infiltration and keratocyte distribution in the corneas, were examined at different time points （1 week, 1 month, 3 months after surgery）. One month after surgery, the adhesion of the corneal flap and corneal stroma was detected by a tensile resistance experiment and the diameters of collagen fibers in each group were compared by electron microscope section of 5 rabbit corneas. The data were analyzed by an independent samples t test and a paired t test. Results Yellow-green riboflavin could be found in the anterior chamber after 20 min, which suggested that riboflavin could penetrate the corneal stroma. There was no difference in corneal edema between the experimental and control groups. And the corneal edema had almost disappeared 3 days after LASIK. When compared to the control group, pathology showed that there was no further infiltration of inflammatory cells in the experimental eyes. There was a ＂no cell zone＂ in both eyes, and there was no difference between them. At different tension lengths, the adhesion of the corneal flap and the corneal stroma in the experimental eyes was stronger than in the control eyes after 1 month （P〈0.01）. In electron microscope sections, mean collagen fiber diameter of the experimental eyes was bigger than in the control eyes （t=7.94, P〈0.01）. Conclusion Animal experiments involving photodynamic corneal erosslinking gruided by riboflavin-ultravilet rays can promote the adhesion and healing of flaps after laser in situ keratomileusis.