Retinal Alterations Produced by Low Level Gallium Arsenide Laser Exposure PDF Download
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Author: Edwin S. Beatrice
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Category :
Languages : en
Pages : 11
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Book Description
The retinas of rhesus monkeys were subjected to irradiation by a prototype gallium arsenide (GaAs) laser training device. The laser device operated at 1600 Hz (pulse repetition frequency mode) or 132 Hz (pulse code mode) with nominal peak pulse power of 1 watt and 10 watts. Exposure durations ranged from 1.0 sec to 90 sec. The tissue reaction at the exposure site was characterized by the development of a pale gray clouding within 10 seconds of initiation of the exposure. The nature of the retinal change could not be determined by ophthalmoscopic, histologic, or flourescein leakage techniques. (Author).
Author: Edwin S. Beatrice
Publisher:
ISBN:
Category :
Languages : en
Pages : 11
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Book Description
The retinas of rhesus monkeys were subjected to irradiation by a prototype gallium arsenide (GaAs) laser training device. The laser device operated at 1600 Hz (pulse repetition frequency mode) or 132 Hz (pulse code mode) with nominal peak pulse power of 1 watt and 10 watts. Exposure durations ranged from 1.0 sec to 90 sec. The tissue reaction at the exposure site was characterized by the development of a pale gray clouding within 10 seconds of initiation of the exposure. The nature of the retinal change could not be determined by ophthalmoscopic, histologic, or flourescein leakage techniques. (Author).
Author:
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Category : Laser materials
Languages : en
Pages : 522
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Category : High power lasers
Languages : en
Pages : 508
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Category : Power resources
Languages : en
Pages : 640
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Author:
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ISBN:
Category : Power resources
Languages : en
Pages : 860
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Author:
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Category :
Languages : en
Pages : 17
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The eyes of 38 anesthetized rhesus monkeys were exposed to near-infrared laser radiation from a repetitive pulse gallium arsenide laser. Pulse repetition frequencies of 40 pps and 1,000 pps were utilized with a 20 nsec. pulse width at the wavelength of 905 nm. Lesions for threshold determination were placed in the temporal paramacular area and could be produced only by varying exposure duration with fixed energy output. Therefore, the resultant 50% probability of damage values (ED-50) were expressed as total exposure duration rather than energy per pulse. The ED-50 value of 0.72 sec. for the 1, 000 pps exposure is significantly lower than the 22.3 sec. for the 40 pps exposure and demonstrates a cumulative effect.
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Category : Military research
Languages : en
Pages : 240
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Category : Military research
Languages : en
Pages : 456
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Category : Toxicology
Languages : en
Pages : 1058
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Author: Randolph D. Glickman
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Category :
Languages : en
Pages : 7
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This article is the result of investigations of retinal function following low-level exposures from an Nd:glass laser, using in vivo recordings of ganglion cell activity from the rhesus monkey retina. Time-dependent effects of laser exposures on rhesus monkey retinal ganglion cells were studied with a Q-switched, doubled Nd:glass laser, which produced 20 nsec pulses of 530-nm light, and a continuous-wave (CW) argon laser (514.5 nm), which produced exposures of 0.1-msec to 0.1-sec duration. Ganglion cell activity was recorded in situ by means of an intraocular electrode. Ganglion cells exposed to a single 20-nsec exposure, at a sublesion intensity, produced a 60-90 sec discharge of action potentials and exhibited a 2 log or greater elevation of light threshold, depending on beam size and intensity. At equivalent energy levels, the longer exposures produced the same or slightly weaker effects. This result is not as straightforward as it seems. Submillisecond flashes bleach no more than 50% of the visual pigment because of photoregeneration. The Dowling-Rushton relation predicts that a 50% bleach should produce only a 1.5 log loss of cone sensitivity. Exposures longer than 1 msec should not photoregenerate pigment (ie, more pigment will be bleached for a given exposure intensity). In view of the probable differences in pigment bleaching, it appears that the Q-switched laser light adapts the cells out of proportion to the visual pigment actually bleached-a single-cell analogue of Rushton's 'theta' effect. Keywords: Q-switched lasers, Neodymium lasers, Argon lasers, Electrophysiology, Reprints. (KT).
