基于HD-OCT的1.319μm近红外激光致兔角膜损伤后早期修复研究

HD-OCT of corneal wound healing of rabbits after 1.319 μm near infrared laser irradiation

目的 以高分辨率光学相干断层扫描仪(HD-OCT)为主要手段,观察1.319μm近红外激光致兔角膜损伤后早期修复过程。方法 波长1.319μm近红外激光损伤10只新西兰白兔右眼角膜,照射剂量140 J/cm2,于损伤前、损伤即刻、1、3、6、12、18、24、30、36、42、48、54、60、66、72 h和7 d共17个时间点,用HD-OCT活体观察角膜损伤横断面特征、测量损伤中心角膜全层和角膜上皮厚度,并于损伤前和损伤后6 h,1、3和7 d,通过裂隙灯显微镜和组织病理观察角膜损伤情况。结果 HD-OCT结果表明,1.319μm激光损伤累及角膜全层,损伤区角膜反射光带增强,随时间发展角膜快速肿胀增厚,于18 h达到最厚,其后水肿逐渐减轻消退;新生上皮自损伤边缘迁移于24 h内完全覆盖损伤区,30 h达到最厚,7 d时厚度基本恢复正常。裂隙灯观察角膜混浊也呈先加重后减轻。组织病理表明,损伤后6 h受损上皮和内皮细胞快速脱落,新生上皮和内皮细胞自损伤边缘向损伤中心迁移,24 h新生上皮完全覆盖损伤区,3 d新生内皮完全覆盖损伤区,7 d上皮层和内皮层基本恢复正常;受损基质细胞染色质脱失,其后炎性细胞从周边浸润损伤区,至7 d水肿虽已基本消退,但仍有大量炎性细胞浸润。结论 1.319μm激光致角膜全层性损伤,历经炎性反应期和损伤修复期,角膜水肿发生迅速,消退缓慢,其时相特性与角膜上皮层和内皮层的破坏与重建相一致。

Objective To observe the wound healing process of corneal injury of rabbits induced by 1.319 μ m infrared laser by means of high-definition optical coherence tomography(HD-OCT). Methods The right corneas of ten New Zealand white rabbits were damaged by near infrared laser at the wavelength of 1.319 μm with corneal radiant exposures of 140 J/cm~2. Cross-sectional features of corneal injury,corneal thickness and new corneal epithelial thickness were measured by HD-OCT before exposure and 0,1,3,6,12,18,24,30,36,42,48,54,60,66,72 h,and 7 d after injury. Slit lamp microscopy and histological evaluation of the corneas were preformed pre-exposure and 6 h,and 1,3,7 d after injury. Results HD-OCT showed that the corneal lesions induced by 1.319 μm laser involved the whole cornea layer,and that the high-reflectance band in the sites of injury was seen clearly. The corneal thickness increased rapidly with time,and reached the maximum at 18 h before the edema was gradually relieved and subsided. Meanwhile,at 24 h,new epithelium around the injury covered the site of injury completely,and the epithelium thicknesses reached the maximum at 30 h before the thickness returned to normal at 7 d. Slit illumination found that the corneal opacity increased first and then subsided. Histological section showed that at 6 h,the necrotic epithelium and endothelium exfoliated quickly,and that the new epithelial and endothelial cells migrated from the edge of injury to the center of injury. New epithelial cells covered the site of injury completely at 24 h,while new endothelial cells covered the site of injury completely at 3 d.At 7 d,the epithelium and endothelium returned to normal. The chromatin of the injured stromal nuclei disappeared before inflammatory cells infiltrated into the damaged area from the surrounding areas. At 7 d,the edema almost dissipated,but there were still a large number of inflammatory cells. Conclusion The corneas lesions induced by1.319 μm laser involve the whole cornea layer. The wound healing process includes inflammation and recovery. Corneal edema develops rapidly and subsides slowly. The temporal properties are consistent with the disruption and reconstruction of the corneal epitheliium and endothelium layer.