Hu X H, Juhasz T
Department of Physics, University of California, Irvine 92717, USA.
Lasers Surg Med. 1996;18(4):373-80. doi: 10.1002/(SICI)1096-9101(1996)18:4<373::AID-LSM6>3.0.CO;2-P.
Corneal ablation has been studied by picosecond laser pulses in the far-UV region.
STUDY DESIGN/MATERIALS AND METHODS: Laser pulses of 25 ps duration at 211 nm and 263 nm wavelengths and a 1 kHz repetition rate have been used to ablate human and rabbit corneas. The dependence of the etch rate on laser fluence has been measured at both wavelengths. The collateral tissue damage has been investigated by electron microscopy.
The ablation threshold for human cornea is determined to be about 3.0 mJ/cm2 at 211 nm, while the thresholds for rabbit cornea are about 2.3 mJ/cm2 at 211 nm and 8.0 mJ/cm2 at 263 nm. The slopes of the ablation curves and the dimensions of the damage zones have also been determined.
We compare these results to the existing data on corneal ablation by nanosecond UV pulses and discuss the deficiency of the photochemical model. Experimental results are analyzed in terms of a model that features plasma ablation assisted by chromophore absorption.
已利用远紫外区域的皮秒激光脉冲对角膜消融进行了研究。
研究设计/材料与方法：使用波长为211nm和263nm、持续时间为25ps且重复频率为1kHz的激光脉冲对人眼和兔眼角膜进行消融。已在这两个波长下测量了蚀刻速率对激光能量密度的依赖性。通过电子显微镜研究了周边组织损伤情况。
确定人眼角膜在211nm处的消融阈值约为3.0mJ/cm²，而兔眼角膜在211nm处的阈值约为2.3mJ/cm²，在263nm处为8.0mJ/cm²。还确定了消融曲线的斜率和损伤区域的尺寸。
我们将这些结果与关于纳秒紫外脉冲角膜消融的现有数据进行比较，并讨论光化学模型的不足之处。根据一个以发色团吸收辅助等离子体消融为特征的模型对实验结果进行了分析。
