飞秒激光对离体兔巩膜的光离解作用

为探索飞秒激光在兔眼巩膜上产生光离解作用的可行性,并寻找适当的激光切割方式及相关参数,将不同脉冲能量的飞秒激光(800nm/50fs)聚焦后作用于离体兔眼巩膜。通过计算机控制的三维平台的定向移动,飞秒激光能够在兔眼巩膜上完成打孔、蛇形扫描和线性切割三种方式的光离解作用。应用光学显微镜和扫描电镜(SEM)观察激光作用后巩膜的形态学变化,并用Nd∶YAG激光作为对比。实验结果表明,飞秒激光经过显微物镜(NA0.2)聚焦后,当其功率密度达到或超过9.55×1014W/cm2,脉冲能量在37.5~125μJ变化时,激光以0.1mm/s的速度线性扫描巩膜能形成深度为30~70μm的沟道;当激光的功率密度减小至7.96×1014W/cm2,脉冲能量小于31.25μJ/pulse时,在相同条件下却不能产生光离解作用。与Nd∶YAG激光相比,飞秒激光在兔眼巩膜上切割瘘道的内壁更加光滑整齐,对周围的组织损伤更小。飞秒激光对离体兔眼巩膜高精度和微创伤的光离解作用,预示了它在未来青光眼治疗中有潜在的应用价值。

Femtosecond Laser Photodisruption in the Rabbit Sclera

In order to explore the possibility of photodisruption in rabbit sclera by femtosecond laser and to seek the appropriate ways of incision and relevant parameters, femtosecond laser (800 nm/50 fs) with different pulse energies was applied to irritate rabbit sclera in vitro. By moving a three-axis, computer-controlled translation stage to which the sample was attached, femtosecond laser could achieve three types of incisions, including transscleral channel, snake pattern and linear cutting. The irritated sclera was observed by light microscopy and scanning electron microscopy (SEM). In comparison with femtosecond laser, Nd:YAG laser was used as control. It was shown that through a 0.2 numerical aperture (NA) objective lens, femtosecond laser with the power intensity larger than 9.55×1014 W/cm2 and the pulse energies ranging from 37.5 to 125 μJ could achieve cuttings with the depth from 30 to 70 μm after linearly scanning on the sclera at the speed of 0.1 mm/s. Whereas, it failed to make any photodisruption if laser power intensity was below 7.96×1014 W/cm2 or the pulse energy was less than 31.25 μJ under the same condition. Comparing with Nd:YAG laser, the inner wall of channel was smoother and the damage to surrounding tissues was slighter by femtosecond laser. The high precision and minimal damage to surrounding tissues with femtosecond laser predicted its potential use in the treatment of glaucoma.