Miller Joe, Yu Xiao-Bo, Yu Paula K, Cringle Stephen J, Yu Dao-Yi
Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia.
Appl Opt. 2011 Feb 20;50(6):876-85. doi: 10.1364/AO.50.000876.
Ultraviolet (UV) lasers have the capability to precisely remove tissue via ablation; however, due to strong absorption of the applicable portion the UV spectrum, their surgical use is currently limited to extraocular applications at the air/tissue boundary. Here we report the development and characterization of a fiber-optic laser delivery system capable of outputting high-fluence UV laser pulses to internal tissue surfaces. The system has been developed with a view to intraocular surgical applications and has been demonstrated to ablate ocular tissue at the fluid/tissue boundary. The fifth (213 nm) and fourth(266 nm) harmonics of a Nd:YAG laser were launched into optical fibers using a hollow glass taper to concentrate the beam. Standard and modified silica/silica optical fibers were used, all commercially available. The available energy and fluence as a function of optical fiber length was evaluated and maximized. The maximum fluence available to ablate tissue was affected by the wavelength dependence of the fiber transmission; this maximum fluence was greater for 266 nm pulses (8.4 J/cm2) than for 213 nm pulses (1.4 J/cm2). The type of silica/silica optical fiber used did not affect the transmission efficiency of 266 nm pulses, but transmission of 213 nm pulses was significantly greater through modified silica/silica optical fiber. The optical fiber transmission efficiency of 213 nm pulses decreased as a function of number of pulses transmitted, whereas the transmission efficiency of 266 nm radiation was unchanged. Single pulses have been used to ablate fresh porcine ocular tissue. In summary, we report a method for delivering the fifth (213 nm) and fourth (266 nm) harmonics of a Nd:YAG laser to the surface of immersed tissue, the reliability and stability of the system has been characterized, and proof of concept via tissue ablation of porcine ocular tissue demonstrates the potential for the intraocular surgical application of this technique.
紫外（UV）激光能够通过消融精确去除组织；然而，由于对紫外光谱适用部分的强烈吸收，其手术应用目前仅限于空气/组织边界处的眼外应用。在此，我们报告了一种能够向内部组织表面输出高能量密度紫外激光脉冲的光纤激光传输系统的开发与特性。该系统是为眼内手术应用而开发的，并已证明能够在液体/组织边界处消融眼组织。使用空心玻璃锥将Nd:YAG激光的第五谐波（213nm）和第四谐波（266nm）发射到光纤中，以集中光束。使用了标准和改性的二氧化硅/二氧化硅光纤，均为市售产品。评估并最大化了作为光纤长度函数的可用能量和能量密度。可用于消融组织的最大能量密度受光纤传输的波长依赖性影响；266nm脉冲（8.4J/cm²）的最大能量密度大于213nm脉冲（1.4J/cm²）。所用二氧化硅/二氧化硅光纤的类型不影响266nm脉冲的传输效率，但通过改性二氧化硅/二氧化硅光纤传输的213nm脉冲明显更大。213nm脉冲的光纤传输效率随传输脉冲数的增加而降低，而266nm辐射的传输效率不变。已使用单脉冲消融新鲜猪眼组织。总之，我们报告了一种将Nd:YAG激光的第五谐波（213nm）和第四谐波（266nm）传输到浸没组织表面的方法，该系统的可靠性和稳定性已得到表征，并且通过猪眼组织消融的概念验证证明了该技术在眼内手术应用中的潜力。
