A light phenomenon perceived when viewing CRT-based VDT screens with positive image.
The present article describes a light phenomenon seen during work with video display terminals with positive image. The phenomenon is perceived for a very short moment as a brightly shining horizontal line when the gaze moves downwards on the screen. The vertical gaze velocity as measured by electro-oculography was 7 to 12 m/s. The vertical velocity of the electron beam on two different terminal screens recorded by photosensitive diodes was 10 m/s. The screens were also rotated 90 degrees , 180 degrees and 270 degrees from normal position. The phenomenon then occurred only when the electron beam line and the gaze moved in the same direction. It is suggested that the light phenomenon is perceived during a short moment when the electron beam line and the gaze move in the same direction with about equal velocity.
Nylén
P
P
Department of Occupational Neuromedicine, National Board of Occupational Safety and Health, Solna, Sweden.