Wu W C, Stark W J, Green W R
Wilmer Institute, Johns Hopkins Medical Institutions, Baltimore, MD.
Arch Ophthalmol. 1991 Oct;109(10):1426-32. doi: 10.1001/archopht.1991.01080100106053.
As part of a human trial of phototherapeutic keratectomy, we performed anterior keratectomy using excimer laser 193-nm ablation on patients with superficial corneal opacities. We examined the ultrastructural changes in the corneas of four patients who underwent penetrating keratoplasty 6 to 15 months after excimer laser ablation. The four cases included macular dystrophy, recurrent keratoconus in a graft, and corneal scarring (two eyes). Light microscopy showed epithelial thickening, absence of Bowman's layer, and superficial stromal scarring in the area of ablation. Ultrastructural study showed that the epithelial basement membrane had focal discontinuities. At the margin of the ablation superficial collagen bundles terminated abruptly in a steplike configuration. The anterior stroma was scarred, with loss of lamellar structure and an increase in number of fibrocytes. The laser-induced scar was 10 to 15 microns thick in the two eyes without a stromal scar before laser ablation. The stroma underlying the scarred areas and that in the untreated area appeared normal. Linear collagen-like fibers were present in the posterior aspect of Descemet's membrane. Laser-induced scarring may be an important factor in limiting visual improvement in patients undergoing phototherapeutic keratectomy.
作为光治疗性角膜切除术人体试验的一部分，我们对患有浅层角膜混浊的患者使用准分子激光193纳米消融术进行了前部角膜切除术。我们检查了4例在准分子激光消融术后6至15个月接受穿透性角膜移植术患者角膜的超微结构变化。这4例包括斑点状营养不良、移植片复发性圆锥角膜和角膜瘢痕形成（2只眼）。光学显微镜检查显示，消融区域上皮增厚、Bowman层缺失以及浅层基质瘢痕形成。超微结构研究显示，上皮基底膜有局灶性连续性中断。在消融边缘，浅层胶原束呈阶梯状突然终止。前部基质形成瘢痕，板层结构消失，纤维细胞数量增加。在激光消融前无基质瘢痕的2只眼中，激光诱导的瘢痕厚度为10至15微米。瘢痕区域下方的基质和未治疗区域的基质看起来正常。Descemet膜后部存在线性胶原样纤维。激光诱导的瘢痕形成可能是限制接受光治疗性角膜切除术患者视力改善的一个重要因素。
