Visual Suppression Test

Abstract

The visual suppression test is one of the visual fixation tests. It is carried out by recording caloric nystagmus by electro-oculography (EOG), and the maximum slow phase velocity of caloric nystagmus in darkness is compared with the slow phase velocity in the light with the eyes open. Visual suppression of the slow phase velocity of caloric nystagmus is 66±11% in normal subjects. Visual suppression in normal subjects is not influenced by the temperature of the water used for the caloric test and not changed by the background illumination in the light. Visual suppression is stronger when the target is closer to the eyes of the subjects. Visual suppression increased when the subjects have been examined repeatedly. The following abnormalities have been diagnosed by this test.
1. Reduced visual suppression (visual suppression, 40%-10%): flocculus and nodulus lesions on the side of the lesion.
2. Abolished visual suppression with the augmentation of caloric nystagmus in light (visual suppression, under 10%): pontine lesions.
3. Reduced or abolished visual suppression with the augmentation of caloric nystagmus in light (visual suppression, under 40%): lower parietal lobe lesions.
4. Increased visual suppression (visual suppression, over 75%): compensation after unilateral sudden loss of inner ear function.