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Introduction: For an accidental laser exposure, the duration of the incident radiation on a specific retinal site depends on the initial fixation, the kinetics of the aversion (blink reflex) and the orienting response (eye movement) toward or away from the light image. Pupilary constriction during the exposure will attenuate the retinal irradiance. Methods: In this study, tracking performance was measured in eight volunteers exposed to O1, LO, and 10 second laser flashes while tracking a dynamic target (O28 degs) through a monocular telescope equipped with a miniature video camera to monitor eye response. The collimated 514 nm argon laser beam produced corneal radiant exposures of 0. 16, 0.33, and LO mJ/cm2 for the 0. 1, LO, and 3O second conditions respectively. Total time off target and maximum absolute error scores were measured for bright (430 nits) and dim (43 nits) ambient luminance conditions. Eye response (blink and pupilary response) was assessed by evaluation of the video from the eye camera. Volunteer reports of the visual experience were recorded. Results: Total time off target (> 0.5 mrad) was maximal for the 3 second exposure condition and minimal for the 0. 1 second conditions. Analysis of the data indicated that there was no photic induced blink reflex for the 0. 1 second condition under the bright light condition. For some volunteers, blinks did occur during the longer duration exposures but were not classic reflex blinks. Pupil responses following the laser presentation showed pupil diameters decreased from initial values of approximately 6 mm to 23 mm which reduced the total energy into the eye at that point by a factor of 10. Volunteers reported smeared and multiple afterimages for the 3 second condition, however, only a single, focal, afterimage was reported for the 0. 1 second condition. This information reflects a history of eye movements during the exposure; Summary: For durations of 100 msec or less, physiological mechanisms that would limit the retinal radiant exposure are not operative for the conditions investigated in this study. For the a 1 second exposure condition, fracking performance was not affected for the bright light vials and only minimally affected foe the dim light trials.
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