title: Lasers' spectral and temporal profile can affect visual glare disability.
abstract: BACKGROUND
  Experiments measured the effects of laser glare on visual orientation and motion perception. Laser stimuli were varied according to spectral composition and temporal presentation as subjects identified targets' tilt (Experiment 1) and movement (Experiment 2). The objective was to determine whether the glare parameters would alter visual disruption.
  
  
  METHODS
  Three spectral profiles (monochromatic Green vs. polychromatic White vs. alternating Red-Green) were used to produce a ring of laser glare surrounding a target. Two experiments were performed to measure the minimum contrast required to report target orientation or motion direction. The temporal glare profile was also varied: the ring was illuminated either continuously or discontinuously. Time-averaged luminance of the glare stimuli was matched across all conditions.
  
  
  RESULTS
  In both experiments, threshold (deltaL) values were approximately 0.15 log units higher in monochromatic Green than in polychromatic White conditions. In Experiment 2 (motion identification), thresholds were approximately 0.17 log units higher in rapidly flashing (6, 10, or 14 Hz) than in continuous exposure conditions.
  
  
  CONCLUSIONS
  Monochromatic extended-source laser glare disrupted orientation and motion identification more than polychromatic glare. In the motion task, pulse trains faster than 6 Hz (but below flicker fusion) elevated thresholds more than continuous glare with the same time-averaged luminance. Under these conditions, alternating the wavelength of monochromatic glare over time did not aggravate disability relative to green-only glare. Repetitively flashing monochromatic laser glare induced occasional episodes of impaired motion identification, perhaps resulting from cognitive interference. Interference speckle might play a role in aggravating monochromatic glare effects.
authors: Naval Medical Research Unit-San Antonio, 3650 Chambers Pass, Fort Sam Houston, TX 78234-6315, USA. jeremy.m.beer.ngo@mail.mil
authors: Jeremy M A
authors: JM
authors: Beer
authors: David A
authors: DA
authors: Freeman
mesh_terms: D000221:Adaptation, Ocular / Q000502:physiology; D000328:Adult; D000704:Analysis of Variance; D001359:Aviation; D015350:Contrast Sensitivity / Q000502:physiology; D005260:Female; D019466:Glare / Q000009:adverse effects*; D006801:Humans; D007834:Lasers / Q000009:adverse effects*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation; D014786:Vision Disorders / Q000209:etiology* / Q000503:physiopathology*; D014787:Vision Tests / Q000379:methods; D014785:Vision, Ocular / Q000502:physiology*