Accession Number : ADA337852

Title :   Laser Irradiation Effects: A Functional Assessment.

Descriptive Note : Final rept. 30 Sep 92-31 Jul 97,

Corporate Author : OHIO WESLEYAN UNIV DELAWARE

Personal Author(s) : Robbins, David O.

PDF Url : ADA337852

Report Date : AUG 1997

Pagination or Media Count : 54

Abstract : Laser damage criteria have traditionally relied on fundoscopic and/or histological evidence. These methodologies have provided limited information regarding the functional impact of observed damage and more importantly, cannot assess the transition zone between temporary and permanent visual loss. Previously we have shown that transient and permanent visual deficits can be produced by long (msec) duration laser pulses at or slightly below traditional threshold levels for retinal The present investigation extended these exposures to include Q-switched, 532 mn Nd/YAG pulses presented to awake, task-oriented nonhuman primates. At and above the ED50, single pulses of minimal spot diameter (50 % produced only minor, transient shifts in acuity although repeated exposures lead to permanent deficits over time. At lower energies (lOX below ED50), minimal spot, single-pulsed exposures produced little observable consequence until either retinal spot sizes or the number of pulses were increased. At these lower energy levels, however, no permanent functions loss was observed. Hence, the functional impact of single nsec pulses was more difficult to assess than longer msec exposures. Multiple nsec pulses and/or larger spot sizes produced visual deficits similar to those observed for msec exposures, suggesting both - temporal and spatial summation at energy levels where no permanent effects have been noted.

Descriptors :   *RETINA, *LASER DAMAGE, *VISUAL ACUITY, THRESHOLD EFFECTS, LIGHT PULSES, DEFICIENCIES, LEVEL(QUANTITY), IRRADIATION, ENERGY LEVELS, LUMINANCE, HISTOLOGY.

Subject Categories : Anatomy and Physiology
      Radiobiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE