[Effect of stabilization of the visual field on rotatory testing]

The nystagmus of 20 normal subjects was compared by means of the rotatory test in the dark, in respect of visual fixation, and with stabilization of vision. Visual fixation was tested by means of a small lamp placed at a distance of 40 cm in front of the eyes of the subject. This point of fixation was attached to the rotating chair. Stabilization of vision was attained through a box placed above the head of the test person. This box - covering the whole visual field - moved synchronously with the rotating chair. Contrary to the test with fixation, the eye received no information about the real movement. The question was whether there would be any differences between the fixation test and the stabilization of vision. In both test conditions, fixation overrides the vestibular stimulus and results in suppressing both per- and postrotational nystagmus. This proves that the foveal vision and not peripheral vision is responsible for the suppression of fixation.