Visual suppression test.

The visual suppression test is one of the visual fixation tests. It is performed by recording caloric nystagmus by ENG, and the maximum slow phase velocity of caloric nystagmus in darkness is compared with the slow phase velocity in light with eyes open. Visual suppression of slow phase velocity of caloric nystagmus is 54 +/- 12% in 52 normal adults ageing from 21 to 40. Visual suppression in normal subjects is not influenced by water temperature used for the caloric test and not changed by background illumination in light. Visual suppression is stronger when the target is closer to the eyes of the subjects. The following abnormalities have been diagnosed by this test: flocculus and nodulus lesions on the side of the lesion; inferior olive lesions; parietal lobe lesions; compensation after unilateral sudden loss of inner ear function.