Krueger R R, Quantock A J, Juhasz T, Ito M, Assil K K, Schanzlin D J
Anheuser-Busch Eye Institute, Dept of Ophthalmology, St Louis University School of Medicine, MO 63104, USA.
J Refract Surg. 1996 Jul-Aug;12(5):607-12. doi: 10.3928/1081-597X-19960701-13.
To investigate the ultrastructure of the corneal stroma after picosecond intrastromal photodisruption with a neodymium-doped yttrium-lithium-fluoride (Nd:YLF) laser.
We performed picosecond intrastromal photodisruption on six human eye-bank eyes using a lamellar technique. Thirty picosecond pulses at 1000 Hz and 20 to 25 mJ per pulse were placed in an expanding spiral pattern, the pulses separated by 15 microns. Three layers were placed in the anterior stroma, separated from each other by 15 microns. In addition, intrastromal radial and arcuate incisions were generated in two living rabbit eyes in a plane perpendicular to the corneal surface. After the procedure, the corneas were processed for scanning and transmission electron microscopy.
Scanning electron microscopy of the eye-bank eyes demonstrated multiple, coalescing intrastromal cavities forming a layer oriented parallel to the corneal surface. These cavities had smooth inner walls. Transmission electron microscopy demonstrated tissue loss surrounding some cavities, with the terminated ends of collagen fibrils clearly evident. Other cavities were formed by separation of lamellae, with little evidence of tissue loss. A pseudomembrane was present along the margin of some cavities. Although there was occasional underlying tissue disruption along the border of a cavity, there was no evidence of thermal damage or tissue necrosis. The perpendicular photodisruptions demonstrated intrastromal cleavage of corneal collagen similar to diamond-knife incisions, with the exception of intact overlying Bowman's and epithelial layers.
Intrastromal photodisruption with a Nd:YLF picosecond laser induced no thermal necrosis or coagulative change in the region of tissue interaction. Lamellar intrastromal photodisruption demonstrated both tissue loss and lamellar separation when performed with the current treatment parameters, possibly limiting ablation efficiency and predictability.
研究掺钕钇锂氟化物（Nd:YLF）激光皮秒基质内光爆破后角膜基质的超微结构。
我们使用板层技术对6只人眼库眼球进行了皮秒基质内光爆破。以1000Hz的频率发射30个皮秒脉冲，每个脉冲能量为20至25mJ，呈扩展螺旋模式放置，脉冲间隔为15微米。在前基质中放置三层，彼此间隔15微米。此外，在两只活体兔眼中，在垂直于角膜表面的平面上制作了基质内放射状和弧形切口。术后，对角膜进行扫描电子显微镜和透射电子显微镜检查。
眼库眼球的扫描电子显微镜显示，多个合并的基质内腔形成了一层与角膜表面平行的层。这些腔的内壁光滑。透射电子显微镜显示，一些腔周围有组织损失，胶原纤维的末端清晰可见。其他腔是由板层分离形成的，几乎没有组织损失的迹象。一些腔的边缘有假膜。虽然在腔的边缘偶尔有潜在的组织破坏，但没有热损伤或组织坏死的证据。垂直光爆破显示角膜胶原的基质内裂解类似于钻石刀切口，只是上方的Bowman层和上皮层完整。
Nd:YLF皮秒激光基质内光爆破在组织相互作用区域未引起热坏死或凝固性改变。在当前治疗参数下进行板层基质内光爆破时，显示出组织损失和板层分离，这可能会限制消融效率和可预测性。
