Download or read book Threshold Damage Evaluation of Long term Exposures to Argon Laser Radiation written by School of Aerospace Medicine and published by . This book was released on 1974 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: The maculae of rhesus monkeys were exposed to an argon-ion laser operated in the TEMoo continuous wave (CW) mode at a wavelength of 514.5 nm. Damage thresholds (ED50) were determined for exposure times of 0.5, 5, 30, and 120 sec. Retinal damage was assessed at both 1-hr and 24-hr postexposure. With increasing exposure times, a 24-hr threshold criterion resulted in significantly lower threshold values, compared to a 1-hr criterion. Threshold values of 0.5 sec using 1-hr and 24-hr evaluation criteria were determined to be 9.4 and 9.0 mW, respectively; for 5 sec, 6.4 and 5.6 mW; for 30 sec, 5.4 and 2.5 mW; and for 120 sec, 4.4 and 0.54 nW. (Author).
Download or read book Evaluation of Retinal Damage Produced by Long Term Exposure to Laser Radiation written by William D. Gibbons and published by . This book was released on 1975 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study reported here was designed with two objectives. The first objective was to determine whether or not photopigments may be involved in the production of 'nonthermal' lesions, and the second objective was to extend argon ED50 measurements for 'nonthermal' lesions to 1000-sec exposures. To accomplish the first objective, exposures were made for 120 seconds using a wavelength of 1060 nm. This wavelength, when absorbed at the retina, can produce a temperature rise but is inefficient in bleaching photopigments. Thus, lesions produced by these exposures should stem primarily from thermal changes. The results of these exposures were then compared to those obtained from exposure to a wavelength of 514.5 nm which readily interacts with photopigments.
Download or read book Mechanisms of Retinal Damage from Chronic Laser Radiation Thresholds and Mechanisms written by Theodore Lawwill and published by . This book was released on 1977 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect upon the retina of exposure to large fields of bright visible light has been evaluated. The thresholds for permanent retinal damage for four hour exposures in rhesus monkeys have been established for white light, and laser lines of 514.5 nm, 488 nm, 457.9 nm, and 590 nm. The damage has been evaluated by ophthalmoscopy, electroretinography and light and electron microscopy. The shortest wavelength light (457.9 nm) is more effective in causing damage, particularly histological damage, which is spread throughout the fundus and throughout the retina layers. Functional damage shown by the electroretinogram follows a different action spectrum without the increased effect in the blue. There appears to be more than one mechanism for retinal damage in chronic light exposure, and at least one mechanism is not dependent solely upon the visual pigment and the pigment epithelium. Thresholds of permanent damage appear to be within one or two log units of light levels encountered in the normal visual environment. Newer data suggest that this damage is additive. Daily one hour exposures for four days produce damage equivalent to a single four hour exposure at the same retinal irradiance. (Author).
Download or read book Ocular Damage Thresholds for Repetitive Pulsed Argon Laser Exposure written by William D. Gibbons and published by . This book was released on 1974 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: The maculae of rhesus monkeys were exposed to radiation from an argon-ion laser operated at a wavelength of 514.5 nm in the TEMoo mode. Damage thresholds were determined for exposure to a single 40 microsec pulse and for different pulse train lengths and repetition rates of 40 microsec wide repetitive pulses. The single pulse threshold was determined to be 2.0 micro J. Thresholds for repetition rates of 100 and 1000 Hz at a pulse train length of 0.5 sec were both found to be 1.0 micro J per pulse. Exposures made at a repetition rate of 100 Hz for pulse train durations of 0.1 and 1.0 sec yielded thresholds of 2.0 and 0.4 micro J per pulse. These data indicate that pulse train length has a greater effect on threshold than repetition rate for the range of parameters studied. (Author).
Download or read book Study of Ocular Effects of Chronic Exposure to Laser Radiation written by T. Lawwill and published by . This book was released on 1973 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: The project is a study of the effects of long term exposure of the eye to laser radiation. The data is for four hour, wide field exposures at levels below immediate damage threshold for rabbit and monkey eyes. The report compares the thresholds for white light and the 514.5 and 488.0 nm lines of the argon laser. From this information a hypothesis is proposed as to the mechanism of damage and methods are proposed to test this hypothesis. If the mechanism can be established, generalizations can be made for different conditions and different light sources.
Download or read book Trends in Retinal Damage Thresholds from 100 Millisecond Near Infrared Laser Radiation Exposures A Study at 1 110 1 130 1 150 and 1 319 Nm written by and published by . This book was released on 2009 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Retinal damage thresholds from 100-millisecond exposures to laser radiation for wavelengths between 1,100 and 1,350nm have never previously been established. We sought to determine the retinal damage threshold for 100- millisecond exposures of near-infrared (NIR) laser radiation wavelengths at 1,110, 1,130, 1,150, and 1,319 nm. These data were then used to create trends for retinal damage thresholds over the 1,100?1,350nm NIR region based upon linear absorption of laser radiation in ocular media and chromatic dispersion of the eye.
Download or read book Research on Ocular Laser Thresholds written by Arthur Vassiliadis and published by . This book was released on 1969 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results of experimental investigations of threshold levels for small retinal lesions are presented. Data for rhesus monkeys include thresholds for a Q-switched neodymium laser, both in the macula and in the paramacular area. In addition, extensive data are presented for argon, helium-neon, and neodymium-YAG laser damage threshold. Exposures of human volunteers to various lasers are reported. The lasers used were Q-switched neodymium and ruby lasers, a long-pulse ruby laser, and an argon laser. A report on the histopathology of retinal injury in rhesus monkeys due to Q-switched neodymium and argon lasers is included. (Author).
Download or read book Ocular Hazards of Picosecond and Repetitive Pulsed Lasers Volume II Argon Ion Laser 514 5 Nm written by J. S. Connolly and published by . This book was released on 1978 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: Retinal damage thresholds were determined for exposures of the maculae of rhesus monkeys to CW and repetitive-pulse trains of argon-ion laser radiation at 514.5 nm in the TEMoo mode. Single-pulse exposures were made at pulsewidths of 2, 10, 40, and 100 microsec and 1, 10, 100, and 500 msec. Repetitive-pulse exposures were made for 27 different combinations: train durations of 0.05, 0.5, 5, and 30 sec; pulse repetition frequencies from 0.10 Hz to 10 kHz and pulsewidths of 10, 40, and 100 microsec and 1 msec. Damage thresholds for mode-locked argon laser pulses at 104 MHz and 250 psec pulsewidth for pulse trains of 9.9-sec, 10-msec, and 10-microsec duration were also measured. For pulsewidths of 10 microsec, there is an apparent cumulative effect provided the repetition frequencies are in the range of approximately 0.1 to approximately 10 Hz. The retina is more sensitive to double-pulse exposures, by a factor of 2 to 3 relative to single-pulse thresholds, when the interpulse spacing is approximately 2.5 sec. Nonthermal damage mechanisms, involving a two-step, two-threshold process, may explain our results. Specifically, for double-pulse configurations, the first acts as a reversible photo-trigger which sensitizes the retina in preparation for the subsequent pulse. The elements of an empirical model have been assembled and appear to account satisfactorily for the observed double-pulse threshold data. (Author).
Download or read book Mechanisms of Retinal Damage from Chronic Laser Radiation written by T. Lawwill and published by . This book was released on 1980 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect upon the retina of exposure to large fields of bright visible light has been evaluated. The thresholds for permanent retinal damage for 4, 1, and 0.25 hour exposures in rhesus or cynomolgus monkeys have been established for laser lines of 514.5 nm, 488 nm, 457.9 nm, and 590 nm. In addition, the effect of distributing the 4 hour exposures in one hour doses separated by intervals of one day or one week has been studied. The damage has been evaluated by opthalmoscopy, electroretinography, fluorescein angiography and light and electron microscopy. The shortest wavelength light (457.9 nm) is more effective in causing damage, particularly histological damage, which is spread throughout the fundus and throughout the retinal layers. There appears to be more than one mechanism for retinal damage in chronic light exposure, and at least one mechanism is not dependent solely upon the visual pigment and the pigment epithelium. The results from our studies suggest that with relatively low intensity, long duration exposures that there is a lack of reciprocity between exposure duration and irradiance level.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on with total page 994 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1989 with total page 596 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiannual, with semiannual and annual indexes. References to all scientific and technical literature coming from DOE, its laboratories, energy centers, and contractors. Includes all works deriving from DOE, other related government-sponsored information, and foreign nonnuclear information. Arranged under 39 categories, e.g., Biomedical sciences, basic studies; Biomedical sciences, applied studies; Health and safety; and Fusion energy. Entry gives bibliographical information and abstract. Corporate, author, subject, report number indexes.
Download or read book Journal of Current Laser Abstracts written by and published by . This book was released on 1976 with total page 852 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of Laser tissue Interaction V written by Steven L. Jacques and published by . This book was released on 1994 with total page 510 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 Preliminary Evaluation of Commercially Available Laser Protective Eyewear Mar 1975 written by United States. Bureau of Radiological Health and published by . This book was released on 1975 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements written by and published by . This book was released on 1975-06-27 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Report USAF School of Aerospace Medicine 1 25 1975 written by and published by . This book was released on 1975 with total page 694 pages. Available in PDF, EPUB and Kindle. Book excerpt:
