DIRECTIONAL DIFFERENCES IN VISUAL ACUITY DURING VERTICAL NYSTAGMUS.

摘要

Twenty naval aviator candidates were exposed to four ramp velocity test profiles generated by the Human Disorientation Device. The head orientation was such that the y (left-right) axis was on the Earth-vertical rotational center of the device,with the resulting alpha y pitch stimulation eliciting vertical nystagmus which was recorded on all four profiles. During two of the profiles,the subjects were required to observe a visual target consisting of a vertically aligned series of dots and to report the duration of the period where dot fusion or target blur occurred as a result of the vertical nystagmus. It was found that during pitch forward angular acceleration resulting in nystagmus with a slow component upward,the loss of visual acuity was of a significantly longer duration than that present during stimulation in the opposite direction. Directional differences in the vertical nystagmus response were also observed. (Author)