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Proceedings Paper

Visual acuity changes in rhesus following low-level Q-switched exposures
Author(s): David O. Robbins; Harry Zwick; Bradley D. Bearden; Brenda S. Evans; Bruce E. Stuck
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Paper Abstract

Previously we have shown that visual deficits can be produced by long duration pulses at or slightly below traditional threshold levels for retinal injury. Initially the deficits produced were only transient shifts in baseline acuity that lasted less than 30 min, but successive exposures over a period of days at these same power levels were shown to be cumulative and their impact on visual acuity lengthened and became permanent. The present investigation extended these exposures to Q-switched, 532 nm Nd/YAG pulses presented to awake, task-oriented nonhuman primates performing Landolt ring discriminations. At and above the ED50, single pulses of minimal spot diameter produced only minor, transient shifts in visual acuity while repeated exposures produced significant shifts in acuity that became permanent over time. At lower energies, minimal spot, single-pulsed exposures again produced little observable consequence until either retinal spot sizes or number of pulses were increased. At these lower energy levels, however, no permanent functional loss was observed. Hence, the functional impact of single Q-switched pulses was more difficult to assess than longer time domain exposures. Multiple, low level Q-switched pulses, and/or larger spot sizes produced visual deficits similar to those observed for msec time domain exposures, suggesting both temporal and spatial summation at energy levels where no permanent effects have been noted.

Paper Details

Date Published: 2 May 1997
PDF: 11 pages
Proc. SPIE 2974, Laser and Noncoherent Ocular Effects: Epidemiology, Prevention, and Treatment, (2 May 1997); doi: 10.1117/12.275231
Show Author Affiliations
David O. Robbins, Ohio Wesleyan Univ. (United States)
Harry Zwick, Walter Reed Army Institute of Research (United States)
Bradley D. Bearden, Walter Reed Army Institute of Research (United States)
Brenda S. Evans, Walter Reed Army Institute of Research (United States)
Bruce E. Stuck, Walter Reed Army Institute of Research (United States)

Published in SPIE Proceedings Vol. 2974:
Laser and Noncoherent Ocular Effects: Epidemiology, Prevention, and Treatment
Bruce E. Stuck; Michael Belkin M.D., Editor(s)

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