Ren Q, Simon G, Legeais J M, Parel J M, Culbertson W, Shen J, Takesue Y, Savoldelli M
Department of Ophthalmology, University of California at Irvine 92715.
Ophthalmology. 1994 May;101(5):883-9. doi: 10.1016/s0161-6420(94)31243-7.
The pulsed ultraviolet 213-nm solid-state laser has been demonstrated as an alternative to the gas argon-fluoride 193-nm excimer laser for photorefractive keratectomy (PRK). The authors studied the clinical course and histopathologic changes occurring in rabbit corneas after PRK with a 213-nm solid-state laser.
The 213-nm output of neodymium:YAG frequency-quintupled laser was used to create 5-mm optical zone ablations in seven pigmented rabbit corneas. The radiant exposure was 250 mJ/cm2 delivered through a computer-controlled scanning delivery system with a spot size of 0.5 mm. The target ablation was 4.0 diopters with an estimated ablation depth of 40 microns. A clinical estimate of corneal epithelial healing and stromal haze was made at intervals over the 3-month study period. Animals were killed immediately after ablation, or at 10 days, 1 month, or 3 months after ablation. Corneal tissue was preserved for light microscopy and transmission electron microscopy at each study interval.
All corneas re-epithelialized within 10 days postoperatively. Anterior stromal haze was clinically visible at 3 days, increased until approximately 1 month, and then gradually decreased over the succeeding 2 months. Residual subepithelial haze was visible at 3 months. Results of histopathologic study documented normal epithelium healing over time; the basement membrane retained its regular thickness and hemidesmosomes were abundant at 3 months. The anterior stroma had an increased number of fibroblasts at 10 days, many of which remained until 1 month. A mild, transient, cellular reaction occurred throughout the thickness of the stroma and the endothelium.
Using the 213-nm ultraviolet solid-state laser with a scanning delivery system, PRK shows a similar clinical course and histopathologic findings to the 193-nm excimer PRK study in rabbits. It is a clinically viable procedure for refractive surgery and requires further human clinical trails to determine its efficacy.
脉冲紫外213纳米固态激光已被证明可替代气体氩氟化物193纳米准分子激光用于准分子原位角膜磨镶术（PRK）。作者研究了用213纳米固态激光进行PRK后兔角膜的临床病程及组织病理学变化。
用钕:钇铝石榴石倍频至五倍频的213纳米激光输出，在7只色素沉着兔角膜上制作5毫米光学区消融。通过计算机控制的扫描传输系统以0.5毫米光斑大小传递250毫焦/平方厘米的辐射暴露量。目标消融量为4.0屈光度，估计消融深度为40微米。在3个月的研究期间定期对角膜上皮愈合和基质混浊进行临床评估。动物在消融后立即处死，或在消融后10天、1个月或3个月处死。在每个研究间隔将角膜组织保存用于光学显微镜和透射电子显微镜检查。
所有角膜在术后10天内重新上皮化。前基质混浊在术后3天临床可见，持续增加至约1个月，然后在随后2个月逐渐减少。术后3个月可见残留的上皮下混浊。组织病理学研究结果表明上皮随时间正常愈合；基底膜保持其正常厚度，3个月时半桥粒丰富。前基质在术后10天纤维母细胞数量增加，其中许多持续至1个月。在基质和内皮的全层发生轻度、短暂的细胞反应。
使用带扫描传输系统的213纳米紫外固态激光，PRK在兔身上显示出与193纳米准分子激光PRK研究相似的临床病程和组织病理学表现。它是一种临床上可行的屈光手术方法，需要进一步的人体临床试验来确定其疗效。
