New and more precise subretinal surgical techniques would be useful in a range of retinal disease... more New and more precise subretinal surgical techniques would be useful in a range of retinal diseases. The purpose of this study is to determine the feasibility of using fiberoptically delivered ultraviolet laser energy to transect or ablate subretinal tissues. Choroid segments dissected from fresh porcine eyes, with or without the retinal pigment epithelium (RPE), were clamped in a fluid bath. Pulsed fourth harmonic (266 nm) of a Nd:YAG laser radiation was delivered via an optical fiber probe at fluence levels between 0.08 and 0.40 J/cm 2 . The tissue was then fixed and sectioned for histological examination. Radiation induced damage was categorized by the degree of tissue disruption and ablation depth. Tissue ablation and the severity of the tissue injury varied with both tissue properties and applied laser parameters. Disruption of Bruch's membrane was typically induced by 10 pulses of 0.30 J/cm 2 or 2 pulses of 0.40 J/cm 2 . Lower radiation doses did not disrupt Bruch's membrane, but did damage the choroidal tissue and produce vacuoles in the underlying choroid. The full thickness of the choroid was ablated by 200 pulses of 0.40 J/cm 2 . The presence of the RPE produced a shielding effect which was greater than would be expected for an equivalent thickness of choroidal tissue. Ablation characteristics of subretinal tissue are highly dependent on the laser parameters used and the type of tissue involved. To perform well controlled laser surgery on subretinal tissues both laser parameters and the properties of the target cells and tissues have to be considered.
Ultraviolet (UV) lasers have the capability to precisely remove tissue via ablation; however, due... more 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=cm 2 ) than for 213 nm pulses (1:4 J=cm 2 ). 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.
We report on a method for delivering high fluence pulsed 266 nm laser radiation to the target tis... more We report on a method for delivering high fluence pulsed 266 nm laser radiation to the target tissue via an optical fiber. The fourth harmonic of a Nd:YAG laser was concentrated using a hollow glass taper and launched into an optical fiber. Fluences of up to 2 J͞cm 2 were routinely output at the tapered optical fiber tip. The maximum fluence generated before failure of the optical fiber was between 3.5 and 8 J͞cm 2. Ablation of ocular tissue was demonstrated using fluences of 1.0 and 0.4 J͞cm 2. The delivery system has the potential for use in intraocular surgical procedures.
Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 2009
Intraocular tissue ablation using an optical fibre to deliver the 5th harmonic of a Nd:YAG. [Proc... more Intraocular tissue ablation using an optical fibre to deliver the 5th harmonic of a Nd:YAG. [Proceedings of SPIE 7163, 71630X (2009)]. Joseph Miller, Xiaobo Yu, Paula K. Yu, Stephen J. Cringle, Dao-Yi Yu. Abstract. We report the ...
New and more precise subretinal surgical techniques would be useful in a range of retinal disease... more New and more precise subretinal surgical techniques would be useful in a range of retinal diseases. The purpose of this study is to determine the feasibility of using fiberoptically delivered ultraviolet laser energy to transect or ablate subretinal tissues. Choroid segments dissected from fresh porcine eyes, with or without the retinal pigment epithelium (RPE), were clamped in a fluid bath. Pulsed fourth harmonic (266 nm) of a Nd:YAG laser radiation was delivered via an optical fiber probe at fluence levels between 0.08 and 0.40 J/cm 2 . The tissue was then fixed and sectioned for histological examination. Radiation induced damage was categorized by the degree of tissue disruption and ablation depth. Tissue ablation and the severity of the tissue injury varied with both tissue properties and applied laser parameters. Disruption of Bruch's membrane was typically induced by 10 pulses of 0.30 J/cm 2 or 2 pulses of 0.40 J/cm 2 . Lower radiation doses did not disrupt Bruch's membrane, but did damage the choroidal tissue and produce vacuoles in the underlying choroid. The full thickness of the choroid was ablated by 200 pulses of 0.40 J/cm 2 . The presence of the RPE produced a shielding effect which was greater than would be expected for an equivalent thickness of choroidal tissue. Ablation characteristics of subretinal tissue are highly dependent on the laser parameters used and the type of tissue involved. To perform well controlled laser surgery on subretinal tissues both laser parameters and the properties of the target cells and tissues have to be considered.
Ultraviolet (UV) lasers have the capability to precisely remove tissue via ablation; however, due... more 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=cm 2 ) than for 213 nm pulses (1:4 J=cm 2 ). 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.
We report on a method for delivering high fluence pulsed 266 nm laser radiation to the target tis... more We report on a method for delivering high fluence pulsed 266 nm laser radiation to the target tissue via an optical fiber. The fourth harmonic of a Nd:YAG laser was concentrated using a hollow glass taper and launched into an optical fiber. Fluences of up to 2 J͞cm 2 were routinely output at the tapered optical fiber tip. The maximum fluence generated before failure of the optical fiber was between 3.5 and 8 J͞cm 2. Ablation of ocular tissue was demonstrated using fluences of 1.0 and 0.4 J͞cm 2. The delivery system has the potential for use in intraocular surgical procedures.
Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 2009
Intraocular tissue ablation using an optical fibre to deliver the 5th harmonic of a Nd:YAG. [Proc... more Intraocular tissue ablation using an optical fibre to deliver the 5th harmonic of a Nd:YAG. [Proceedings of SPIE 7163, 71630X (2009)]. Joseph Miller, Xiaobo Yu, Paula K. Yu, Stephen J. Cringle, Dao-Yi Yu. Abstract. We report the ...
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