Repeatability of the Subjective Visual Vertical and Horizontal

Abstract

The Subjective Visual Vertical [SVV] is the angle between the gravitational vertical axis and the position of a linear visual marker adjusted vertically by a subject. The Subjective Visual Horizontal [SVH] is similarly defined. Both SVV and SVH are reported to represent function of otoliths and vertical semicircular canals. Current practice of measuring SVV and SVH uses an average of multiple readings to obtain a mean value. This prospective study investigates repeatability of these tests in controls and patients with peripheral vestibular pathology. Twelve replicate readings of SVV and SVH were recorded in 17 controls, 9 patients with unilateral peripheral vestibular dysfunction [uPVD] and 10 patients with definite Menière's disease [MD]. Control subjects repeated the measurements on day 8 and day 30 and patient groups repeated the measurements one hour later, due to limitations of compliance. Mean SVV/SVH and indicators of repeatability were computed and compared between patients and controls. Repeatability of the readings improves in controls on subsequent sessions and depends on the sequence of readings and inclination of the preset angle to a varying degree in controls and patients. Accounting for these intrasubject variables improves repeatability of SVV and SVH.

• saccule and utricle
• vestibular function tests
• visual perception
• reproducibility of results