“…fs ultrashort pulsed lasers for enclosure of corneal neovascularization in the presence of ICG at 3.8 J/cm 2 was employed by Sawa et al in 2004 [35]. The MVL threshold values determined in the current study are in good agreement with previous reports [12, 19, 35], despite that no dye or photodynamic chemical agents were applied during the procedures.Fig. 3Sequential optical images taken from Norway brown rat cornea before and after the exposure of fs laser irradiation with variation of the laser fluence of 2.2 J/cm 2 ( a ), 4.3 J/cm 2 ( b ), 6.5 J/cm 2 ( c ), and 8.6 J/cm 2 ( d ).…”
Section: Resultssupporting
confidence: 90%
“…The selectivity may come from the difference in damage threshold for the different nature of targeted tissues [12, 17–19, 22, 29]. We have already reported that the quaternary blood vessels with wall thickness of about 6 μm of enucleated porcine retina have optoperforation threshold fluence about four times lower than that for retina itself.…”
Section: Resultsmentioning
confidence: 99%
“…However, the fluence employed in our system (8.6 J/cm 2 ) is lower than the existing fluences. One of the possible reasons for this is shortened pulse width (150 fs) [11, 12, 14–17, 22] along with the difference in spectral range utilized in our system (800 nm).Fig. 9Plot of the red intensity of fs laser-treated cornea ( red-filled bar ) and untreated cornea ( black-filled bar ) and the percent reduction ( green-filled circles ) of neovascular structures as a function of elapsed time after fs laser irradiation with laser fluence of 8.6 J/cm 2 .…”
Section: Resultsmentioning
confidence: 99%
“…Femtosecond (fs) laser ablation of a material meanwhile yields negligible thermal damage [ 10 , 11 ]. The damage induced by the fs laser is furthermore restricted to the size of the laser spot with a localized ablation depth ( l ), which is estimated by the expression l = δ ln ( F / F th δ ), where F th δ and δ are the ablation threshold fluence and optical penetration depth, respectively [ 10 , 12 , 13 ]. Furthermore, the photochemical effect induced by free electrons generated through multiphoton absorption dominates at a lower fluence range (<25.3 J/cm 2 for porcine retina) [ 12 ].…”
Section: Introductionmentioning
confidence: 99%
“…A low ablation threshold upon irradiating a material with an ultrafast laser pulse is thus generally favorable for minimizing possible photo-induced damage near the ablation area [ 14 , 15 ]. In addition, local ablation of various materials such as biological tissues or metals can be efficiently achieved if the laser fluence is precisely controlled [ 6 , 12 , 14 – 17 ]. With systematic control of the fs laser fluence, induction of either transient or permanent changes in various cellular compartments including cell walls, plasma membranes, and even organelles is possible.…”
Nonlinear multiphoton absorption induced by focusing near infrared (NIR) femtosecond (fs) laser pulses into a transparent cornea allows surgery on neovascular structures with minimal collateral damage. In this report, we introduce an fs laser-based microsurgery for selective treatment of rat corneal neovascularizations (in vivo). Contiguous tissue effects are achieved by scanning a focused laser pulse below the corneal surface with a fluence range of 2.2–8.6 J/cm2. The minimal visible laser lesion (MVL) threshold determined over the corneal neovascular structures was found to be 4.3 J/cm2. Histological and optical coherence tomography examinations of the anterior segment after laser irradiations show localized degeneration of neovascular structures without any unexpected change in adjacent tissues. Furthermore, an approximately 30 % reduction in corneal neovascularizations was observed after 5 days of fs laser exposure. The femtosecond laser is thus a promising tool for minimally invasive intrastromal surgery with the aid of a significantly smaller and more deterministic photodisruptive energy threshold for the interaction between the fs laser pulse and corneal neovascular structures.
“…fs ultrashort pulsed lasers for enclosure of corneal neovascularization in the presence of ICG at 3.8 J/cm 2 was employed by Sawa et al in 2004 [35]. The MVL threshold values determined in the current study are in good agreement with previous reports [12, 19, 35], despite that no dye or photodynamic chemical agents were applied during the procedures.Fig. 3Sequential optical images taken from Norway brown rat cornea before and after the exposure of fs laser irradiation with variation of the laser fluence of 2.2 J/cm 2 ( a ), 4.3 J/cm 2 ( b ), 6.5 J/cm 2 ( c ), and 8.6 J/cm 2 ( d ).…”
Section: Resultssupporting
confidence: 90%
“…The selectivity may come from the difference in damage threshold for the different nature of targeted tissues [12, 17–19, 22, 29]. We have already reported that the quaternary blood vessels with wall thickness of about 6 μm of enucleated porcine retina have optoperforation threshold fluence about four times lower than that for retina itself.…”
Section: Resultsmentioning
confidence: 99%
“…However, the fluence employed in our system (8.6 J/cm 2 ) is lower than the existing fluences. One of the possible reasons for this is shortened pulse width (150 fs) [11, 12, 14–17, 22] along with the difference in spectral range utilized in our system (800 nm).Fig. 9Plot of the red intensity of fs laser-treated cornea ( red-filled bar ) and untreated cornea ( black-filled bar ) and the percent reduction ( green-filled circles ) of neovascular structures as a function of elapsed time after fs laser irradiation with laser fluence of 8.6 J/cm 2 .…”
Section: Resultsmentioning
confidence: 99%
“…Femtosecond (fs) laser ablation of a material meanwhile yields negligible thermal damage [ 10 , 11 ]. The damage induced by the fs laser is furthermore restricted to the size of the laser spot with a localized ablation depth ( l ), which is estimated by the expression l = δ ln ( F / F th δ ), where F th δ and δ are the ablation threshold fluence and optical penetration depth, respectively [ 10 , 12 , 13 ]. Furthermore, the photochemical effect induced by free electrons generated through multiphoton absorption dominates at a lower fluence range (<25.3 J/cm 2 for porcine retina) [ 12 ].…”
Section: Introductionmentioning
confidence: 99%
“…A low ablation threshold upon irradiating a material with an ultrafast laser pulse is thus generally favorable for minimizing possible photo-induced damage near the ablation area [ 14 , 15 ]. In addition, local ablation of various materials such as biological tissues or metals can be efficiently achieved if the laser fluence is precisely controlled [ 6 , 12 , 14 – 17 ]. With systematic control of the fs laser fluence, induction of either transient or permanent changes in various cellular compartments including cell walls, plasma membranes, and even organelles is possible.…”
Nonlinear multiphoton absorption induced by focusing near infrared (NIR) femtosecond (fs) laser pulses into a transparent cornea allows surgery on neovascular structures with minimal collateral damage. In this report, we introduce an fs laser-based microsurgery for selective treatment of rat corneal neovascularizations (in vivo). Contiguous tissue effects are achieved by scanning a focused laser pulse below the corneal surface with a fluence range of 2.2–8.6 J/cm2. The minimal visible laser lesion (MVL) threshold determined over the corneal neovascular structures was found to be 4.3 J/cm2. Histological and optical coherence tomography examinations of the anterior segment after laser irradiations show localized degeneration of neovascular structures without any unexpected change in adjacent tissues. Furthermore, an approximately 30 % reduction in corneal neovascularizations was observed after 5 days of fs laser exposure. The femtosecond laser is thus a promising tool for minimally invasive intrastromal surgery with the aid of a significantly smaller and more deterministic photodisruptive energy threshold for the interaction between the fs laser pulse and corneal neovascular structures.
IVbiological tissue to improve the efficacy of laser-based photo-thermal therapy. Chapter 3 discusses the modelling of laser-irradiated biological tissue to understand its thermal behavior, which may help to improve the efficacy of laser-based photothermal therapy. In this study, the light propagation through the biological tissue is mathematically modelled using the heat transfer equation (RTE). RTE is solved using the discrete ordinate method (DOM) to determine the intensity inside the laser-irradiated biological tissue. Consequently, the absorbed photon energy acts as the source term in the Fourier/non-Fourier model-based bio-heat transfer equation to determine the temperature distribution inside the biological tissue subjected to short-pulse laser irradiation.Laser surface texturing is a top-down method for generating surface patterns on polymers, metals, ceramics, glasses, and alloys. This technique allows large-scale surface patterning. Chapter 4 describes the use of a femtosecond laser in micro-/ nano-texturing for fabricating coated and surface-treated dies with tailored textures. Through the femtosecond laser micro−/nano-texturing and CNC-imprinting, the metal, polymer, and glass product surfaces were optically decorated to have color grading and plasmonic brilliance and functionally controlled to be hydrophobic. The proposed approach can be used for micro−/nano-texturing of various industrial and medical products.The interactions of concentrated energy fluxes such as femtosecond lasers and highenergy electron beams with absorbing substances have facilitated new discoveries and excitement in various scientific and technological areas. For instance, femtosecond laser ablation is an effective technique to functionalize surfaces. Due to the ultrashort pulse width and high light intensity (1012 W/cm2), it is possible for the laser to ablate or irreversibly modify the materials with negligible damage outside the focal volume, thereby allowing treatment of biological samples like live cells, membranes, and removal of thin films as well as bulk materials for many applications in diverse fields including micro-optics, electronics, and even biology under extremely high precision. Chapter 5 discusses the ablation of materials using femtosecond lasers and electron beams. Both femtosecond laser and e-beam ablations are being investigated for a range of medical applications. This book is written by experts in the field and is a useful resource for researchers, engineers, and advanced students in the field of photonics, lasers, ultrafast optics, material processing, and medical physics.
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