Farid Marjan, Morishige Naoyuki, Lam Larry, Wahlert Andrew, Steinert Roger F, Jester James V
Gavin S Herbert Eye Institute, University of California, Irvine Medical Center, Orange, California 92868, USA.
Invest Ophthalmol Vis Sci. 2008 Oct;49(10):4377-83. doi: 10.1167/iovs.08-1983. Epub 2008 May 23.
Recent studies have shown that confocal imaging of second harmonic-generated (SHG) signals can detect corneal collagen organization. The purpose of this study was to assess whether SHG signals can detect differences in corneal fibrosis after excimer laser surface ablation (photorefractive keratectomy [PRK]).
Rabbits received 9-D PRK in one eye followed by treatment with either mitomycin C (MMC) or vehicle. Corneal haze was measured by in vivo confocal microscopy before and 2, 4, 8, and 12 weeks after surgery. Animals were then killed and corneas were evaluated by visible and nonlinear confocal microscopy.
PRK induced significant haze in vehicle-treated corneas that peaked at 2 weeks and remained elevated at 12 weeks after surgery. MMC treatment significantly (P < 0.05) reduced corneal haze at 2 weeks and was essentially normal by 12 weeks. Imaging of SHG signals in vehicle-treated eyes showed an anterior layer of collagen forming a honeycomb network blending into a dense mat of irregularly arranged collagen fibers that overlaid normal orthogonally arranged collagen lamellae. MMC treatment showed normal collagen organization at the surface. Fibrotic tissue was associated with a high cell density and alignment of intracellular actin filaments with collagen fiber bundles. In MMC-treated eyes, an anterior acellular zone overlaid a sparsely populated stroma containing isolated and enlarged keratocytes.
Imaging of SHG signals provides a sensitive means for detection of corneal fibrosis after surface ablation and can be used to assess the effects of antifibrotic therapy on corneal healing after refractive surgery.
近期研究表明，二次谐波产生（SHG）信号的共聚焦成像可检测角膜胶原组织。本研究的目的是评估SHG信号能否检测准分子激光表面切削术（光性屈光性角膜切削术[PRK]）后角膜纤维化的差异。
兔一只眼接受9-D的PRK，随后用丝裂霉素C（MMC）或赋形剂治疗。在手术前以及术后2、4、8和12周通过体内共聚焦显微镜测量角膜混浊度。然后处死动物，通过可见光和非线性共聚焦显微镜评估角膜。
PRK在接受赋形剂治疗的角膜中引起显著混浊，在术后2周达到峰值，并在12周时仍保持升高。MMC治疗在2周时显著（P<0.05）降低了角膜混浊度，到12周时基本恢复正常。接受赋形剂治疗的眼中SHG信号成像显示，前部胶原层形成蜂窝状网络，融入覆盖正常正交排列胶原板层的不规则排列胶原纤维致密层。MMC治疗显示表面胶原组织正常。纤维化组织与高细胞密度以及细胞内肌动蛋白丝与胶原纤维束的排列有关。在接受MMC治疗的眼中，前部无细胞区覆盖着细胞稀疏的基质，其中含有孤立且增大的角膜细胞。
SHG信号成像为检测表面切削术后角膜纤维化提供了一种灵敏的方法，可用于评估抗纤维化治疗对屈光手术后角膜愈合的影响。
