Abstract
Disability glare impairs vision and is caused by both intraocular scattering and veiling luminance from extraocular stray light such as scatter from a canopy. The FAA is concerned about increasing incidents of laser exposures of aircraft and is investigating the effects of lasers on the vision of pilots. This study examined the effect of green laser irradiance on orientation discrimination of Gabor patches up to 55 degrees from a laser glare source. Stimulus viewing was centrally with the left eye. Nine subjects participated. They viewed the stimuli with central vision through a Cessna canopy, with and without the laser blocked by a 6 degree opacity. Blocking the central beam source separates the effect of extraocular scatter from intraocular scatter. The stimuli were Gabor patterns, 50% contrast, tilted left or right. Laser irradiance varied from 0.6 microwatts/cm2 to 600 microwatts/cm2, in 0.5 log steps. One degree targets were obscured at 5 degrees from the laser source by 60 µW/cm2 (12 lux) with a 30 cd/m2 background and 6 µW/cm2 with a 3.2 cd/m2 background. With the laser source blocked and a canopy present, 190 µW/cm2 were required to obscure the 1 degree stimuli at 5 degrees for the dimmer background and 19 µW/cm2 for the brighter background. Large 10 degree targets on axis with the laser source were obscured by 60 µW/cm2 with a 30 cd/m2 background and 6 µW/cm2 with a 3.2 cd/m2 background. The results were evaluated in terms of the CIE disability glare functions.