Niemz M H, Klancnik E G, Bille J F
Department of Ophthalmology, La Jolla, University of California, San Diego 92093-0946.
Lasers Surg Med. 1991;11(5):426-31. doi: 10.1002/lsm.1900110507.
Plasma-mediated ablations were performed on human donor corneas with a short pulsed Nd:YLF laser system at 1053 nm. The pulses were 60 psec in duration at a repetition rate of 1.0 kHz. The laser beam was oriented perpendicular to the cornea surface. The threshold energy densities for ablation of epithelium, Bowman's membrane and stroma were measured. They were 6.1 +/- 1.8 J/cm2, 21.0 +/- 5.1 J/cm2 and 10.4 +/- 1.8 J/cm2, respectively. The mean rate of tissue removal at the stromal energy density threshold was about 1 micron per pulse. The walls of the laser excisions were smooth with distortions of less than 1 micron. A new quantitative model of plasma-mediated ablation is introduced and found to closely predict the observed results. Based on the promising nature of the experimental data further investigations are planned in the use of a mode locked Nd:YLF laser as an alternative to excimer lasers for refractive corneal surgery.
使用波长为1053nm的短脉冲Nd:YLF激光系统对人供体角膜进行等离子体介导的消融。脉冲持续时间为60皮秒，重复频率为1.0kHz。激光束垂直于角膜表面定向。测量了上皮、Bowman膜和基质消融的阈值能量密度。它们分别为6.1±1.8J/cm²、21.0±5.1J/cm²和10.4±1.8J/cm²。在基质能量密度阈值下，组织去除的平均速率约为每脉冲1微米。激光切除的壁很光滑，变形小于1微米。引入了一种新的等离子体介导消融的定量模型，发现该模型能很好地预测观察结果。基于实验数据的良好前景，计划进一步研究使用锁模Nd:YLF激光作为准分子激光用于角膜屈光手术的替代方案。
