Download or read book Effects on Ocular Tissue of Multiple Laser Pulses and of Single Ultrashort Pulses of Varying Wavelength written by and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to evaluate laser safety standards, Dr. Toth examined fluorescein angiograms (in some cases OCT) and fixed tissue sections and aided in defining exposure limits for pulse widths less than one nanosecond. In our initial short pulse study, we were concerned with the restriction to a single wavelength. To verify that the tissue effects were due to the pulse structure, we obtained data outside a single wavelength. We obtained from information from -530-nm and -1060nm wavelengths to compare to data obtained from previous studies of visible laser picosecond and femtosecond pulses. The type of lesions created with 530 and 1060-1064nm wavelengths were similar to the lesions created in the earlier 580-nm wavelength studies. This supported the theory that laser induced breakdown is one of the primary damage mechanisms for ultrashort laser pulses. Data from our studies was used by the American National Standard Institute in publications ANSI Z136.1, 'Safe Use of Lasers' (updated 2000) and ANSI Z136.3, 'Safe Use of Lasers in Health Care Facilities' (1996).
Download or read book Ultrashort Laser Pulse Effects on Ocular Tissue Histopathologic Analysis and Surgical Techniques written by Cynthia Toth and published by . This book was released on 1998 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Toth et al. identified the acute pathologic retinal events which determined the extent of tissue damage from minimal laser energy and suprathreshold energy. She identified the acute pathology of primate maculas with minimal visible retinal lesions generated by 90 femtosecond and 5 picosecond pulses of 580 nm laser energy. Dr. Toth's study included light microscopic evaluation of macular damage and electron microscopic ultrastructural analysis of melanosome ruptures within the retinal pigment epithelium. The pathology was reported at AFOSR with a CDROM summary of lesion data provided to armstrong Laboratory for reference. Dr. Toth scored the area and extent of tissue damage and compiled a list for Dr. Rockwell and Dr. Clarence Cain at Armstrong Laboratory, Brooks, AFB for analysis and comparison to the ED50 MVL data. A paper summarizing this work has been published as the lead article in October, 1997 in Investigative Ophthalmology and Visual Science (I0VS). Dr. Toth's Laboratory group gathered significant tissue data on ultrashort pulses of other laser wavelengths. They collaborated with Armstrong Laboratory (Dr. Cain et al.) in analyzing near-infrared ultrashort laser pulse injury MVL data which was published at Society of Photo-Optical Instrumentation Engineers (SPIE), 1997 (Cain, Toth, et al.).
Download or read book Selected Papers on Ultrashort Laser Pulse Bioeffects written by William P. Roach and published by SPIE-International Society for Optical Engineering. This book was released on 2002-12-31 with total page 694 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains key papers that document the initial probing of the limits of subnanosecond pulses and the resulting discoveries of nonlinear effects. The papers tell the story of effects previously thought to be impossible to produce in tissue. If you read all the references carefully, you will see the studies evolve from speculation to experimentation to theory, and culminate in policy recommendations.
Download or read book Ultrashort Pulse Laser Effects in the Primate Eye written by and published by . This book was released on 1994 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: Minimum visible lesion (MVL) threshold measurements at the retina for rhesus monkey eyes are reported for femtosecond, picosecond, and nanosecond single laser pulses using visible wavelengths. Estimates of the dose causing 50% probability for damage (ED50) are calculated for 1-hour and 24-hours postexposure as well as the 95% fiducial intervals for ED. The ED values are found to be dependent on both wavelength and pulsewidth, and for a single wavelength are, in general, lower for short pulsewidths, with the exception of values at the shortest pulsewidth of 90 fs at 580 nm. At 90 fs the ED(50) dosages were noted to increase slightly when compared with the 3-ps and 600-fs values, all three delivered at 580-nm wavelength. The 4-ns ED(50) value was more than double the value at 60 ps delivered at 532-nm wavelength. Fluorescein angiography was accomplished at 1-hour and 24-hours postexposure and did not demonstrate lower threshold for damage, which has been the case for MVLs created with longer pulse duration (greater than 1 ns) or for rabbit eyes at the same pulse-widths as measured in our laboratory.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 542 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ultrashort Laser Pulse Effects in Ocular and Related Media Laser Induced Shock Wave Propagation and Retinal Damage written by T. F. Deutsch and published by . This book was released on 1994 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goals of this project are: (1) To develop assays for functional damage to retinal cells by pressure waves (stress transients); (2) To determine the acoustic properties of the aqueous and vitreous humors of the eye; and (3) To examine the effect of pressure waves to the retinal pigment epithelium in vitro. During this first year our efforts have been directed primarily at the first goal, with some initial efforts on the second. During this period we developed the capability of growing human retinal pigment epithelium (RPE) cells in culture, incorporating them intest capillaries, recovering them after exposure to stress transients and assessing cell damage.
Download or read book Copeland and Afshari s Principles and Practice of Cornea written by Robert A. Copeland and published by JP Medical Ltd. This book was released on 2013-02-28 with total page 1666 pages. Available in PDF, EPUB and Kindle. Book excerpt: The cornea is the transparent front part of the eye covering the iris and the pupil, allowing light to enter and covering two thirds of the eye’s focusing tasks. This two volume set is a comprehensive guide to the latest research and techniques for the cornea. Beginning with basic science, examination techniques and epidemiology, the following chapters discuss the diagnosis and the medical and surgical treatment of numerous different conditions and diseases that may affect the cornea. Written by an extensive international editor and author team, this manual features more than 1300 full colour clinical and histopathological images, as well as a DVD demonstrating a multitude of surgical techniques described in the book. Key points Comprehensive two volume set describing diagnosis and treatment of numerous corneal disorders Features more than 1300 colour images and illustrations Includes a DVD demonstrating surgical techniques and procedures Extensive international author and editor team
Download or read book Toxicology Research Projects Directory written by and published by . This book was released on 1978 with total page 1058 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ocular Effects of Repetitive Laser Pulses written by and published by . This book was released on 1972 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: An argon-ion laser was used to investigate the ocular effects of repetitive laser pulses on rhesus monkeys. The primate eyes were irradiated by trains of pulses held constant at 10 milliseconds, and the duration of the trains was kept uniform at 0.5 sec. The pulse repetition rate was used as a parameter and this parameter was varied to take on the values of 2 Hz(single pulse), 10 Hz, 100Hz, 1 kHz and 10 kHz. Retinal burn thresholds were determined based on the 1 hr criterion for the appearance of ophthalmoscopically visible lesions.
Download or read book Ultrashort Laser Pulses in Biology and Medicine written by Markus Braun and published by Springer. This book was released on 2010-11-18 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Learn about the many biological and medical applications of ultrashort laser pulses. The authors highlight and explain how the briefness of these laser pulses permits the tracing of even the fastest processes in photo-active bio-systems. They also present a variety of applications that rely on the high peak intensity of ultrashort laser pulses. Easy-to-follow examples cover non-linear imaging techniques, optical tomography, and laser surgery.
Download or read book Laser Induced Acoustic and Shock Waves in Ocular Tissues written by and published by . This book was released on 1995 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: Analytical expressions that describe the generation and propagation of acoustic and shock waves in biological tissues are presented. Several practical situations of laser irradiation of various ocular tissues have been considered and these include thermoelastic generation of acoustic waves, linear and nonlinear effects that occur upon propagation of stress transients in tissues, cylindrical shock wave generation upon plasma optical breakdown in the caustic of a focused laser beam, and spherical shock wave generation upon thermal explosion of melanosomes. The transformation of light energy into heat and then to mechanical stress is analyzed for ultrashort-pulse laser irradiation of absorbing tissues, and thermo-optical generation of high-amplitude acoustic waves and the formation of shock waves are reviewed. Stress wave alteration upon propagation through various media is considered along with acoustic wave reflection from boundaries and acoustic wave transmission through interfaces. Finally, nonlinear propagation of high-amplitude acoustic waves is covered.
Download or read book Ultrashort Pulse Laser Technology written by Stefan Nolte and published by Springer. This book was released on 2015-10-19 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultrashort laser pulses with durations in the femtosecond range up to a few picoseconds provide a unique method for precise materials processing or medical applications. Paired with the recent developments in ultrashort pulse lasers, this technology is finding its way into various application fields. The book gives a comprehensive overview of the principles and applications of ultrashort pulse lasers, especially applied to medicine and production technology. Recent advances in laser technology are discussed in detail. This covers the development of reliable and cheap low power laser sources as well as high average power ultrashort pulse lasers for large scale manufacturing. The fundamentals of laser-matter-interaction as well as processing strategies and the required system technology are discussed for these laser sources with respect to precise materials processing. Finally, different applications within medicine, measurement technology or materials processing are highlighted.
Download or read book Laser and Noncoherent Light Ocular Effects written by and published by . This book was released on 2001 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of Laser tissue Interaction written by and published by . This book was released on 1994 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Femtosecond Laser Techniques and Technology written by and published by JAYPEE BROTHERS MEDICAL PUBLISHERS PVT. LTD.. This book was released on 2012-12-15 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book Femtosecond Laser: Techniques and Technology provides complete insight of Femtosecond Laser technology in various ocular indications. Refractive Surgery technology has undergone rapid advancements and innovations in last two decades. Femtosecond Laser offers new possibilities in the field of minimally invasive corneal surgery. It employs near infrared pulses to cut tissue with minimal collateral tissue damage. The highly localized tissue effect of low energy Femtosecond Laser shall expand the capabilities and precision of this technology in near future and may be used to create three-dimensional intrastromal resection with micron precision. Femtosecond laser is a simple, rapid reliable and efficient method in ophthalmology with satisfactory results for effective lens position and refractive outcome. Femtosecond laser is enjoying rapid growth in the area of cataract surgery. The Femtosecond Laser has proved its versatility in Lamellar keratoplasty, customized trephination in penetrating keratoplasty, tunnel creation for intracorneal ring segments, astigmatic keratotomy for keratoprostheses, non-invasive trans-scleral glaucoma surgery, retinal imaging presbyopic surgery and cataract surgery. Advances in ultrafast laser technology continued to improve the surgical safety, efficiency, speed and versatility of Femtosecond Lasers in Ophthalmology. Femtosecond Laser finds application in anterior and posterior segment indications of ophthalmology.
Download or read book Mechanisms and Diagnostics of Ultrashort Pulse Laser Ocular Effects written by James G. Fujimoto and published by . This book was released on 1994 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of our program is to investigate the mechanisms of ultrashort pulse laser retinal injury and to develop and apply new diagnostics for the assessment of retinal injury. During the past contract period, we have focused on the development of a new diagnostic technique called optical coherence tomography (OCT) for the noninvasive measurement of ocular and retinal structure.
Download or read book Laser Radiation Effects on the Morphology and Function of Ocular Tissue written by Arthur E. Jones and published by . This book was released on 1969 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of different energy levels of ruby laser radiation on electrophysiological, psychophysical and anatomical measures were examined. Spectral sensitivity tests, using an ERG analysis, demonstrated prolonged laser effects on rhesus and mangabey monkeys. At 15-months post-exposure for the rhesus monkey (0.8J/sq cm), the amplitude of the b wave was depressed at all wavelengths except 420 nm. At one-year post-laser exposure for the mangabey monkey (0.2J/sq cm), the amplitude of the b wave was depressed at all wavelengths and the amplitude of the b wave as a function of intensity at 570 nm was depressed by about 20 percent at high intensity and not affected at low intensity. Also, the third oscillatory potential remained absent. An ERG analysis of the Rayleigh match demonstrated that rhesus monkeys have normal color vision (A.Q. = 1.0), that squirrel monkeys are protanomalous (A.Q. = 0.305), and that owl monkeys are monochromatic (A.Q. = infinity). Following laser exposure of two rhesus monkeys the match was unbalanced in favor of the green component, indicating a protanomalous response. Behavioral studies of two rhesus monkeys, one laser exposed at 1.8J/sq cm and one exposed at 0.18J/sq cm, demonstrated a reduction in sensitivity at all but two spectral points for the monkey exposed at 1.8J/sq cm and no significant change in the sensitivity of the monkey exposed at 0.18J/sq cm. The latter monkey did, however, show a marked change in the shape of the function indicating an anomalous finding. (Author).
