Static subjective visual vertical (SVV) in the normal visual system
Reviewed by Claire Howard

Graviception is the perception of a persons’ orientation relative to gravitational force. This can be measured by means of subjective verticals, which can be divided into three tests: subjective visual vertical (SVV), subjective postural vertical (SPV) and subjective haptic vertical (SHV). The SVV is an easily applicable test which aims to detect otolithic imbalance. It is tested in complete darkness, in order for visual references to be excluded, and in an upright sitting position, so that proprioceptive inputs contribute only minimally. The test is a sensitive indicator for brainstem dysfunction. This study assessed the SVV in 24 healthy volunteers with varying preset angles. In addition, another 20 volunteers were assessed for test-retest variability; their static SVV was tested and then retested one week later. Results showed that the static SVV results are influenced by the side of the preset angle, but not by the preset angle deviation. The test-retest static SVV outcomes are stable at a group level, however they show statistically relevant variability at an individual level. This paper describes a robust static SVV protocol combining monocular and binocular static SVV measurements. 

Static subjective visual vertical in healthy volunteers: the effects of different preset angle deviations and test-retest variability.
Venhovens J, Meulstee J, Verhagen WIM.
NEURO-OPHTHALMOLOGY
2016;40(3):113-9.