Drift of Visually Induced Optostatic Torsion

Abstract

Purpose: Compensatory ocular torsion has been found in response to static tilted visual stimuli. The purpose was to investigate if visually induced ocular torsion is maintained during continuous stimulation and to reinvestigate the effect of stimuli tilt angle. Methods: Eye movements were recorded in 19 healthy individuals using a 3-D video oculography system. One visual stimulus was used in the tests, a photographic image of a city scene with spatial clues relevant for body posture. The scenes were tilted counterclockwise around a central pivot point from 0 to 15 degrees (test A), from 0 to 30 degrees (test B), and from 0 to 45 degrees (test C). Each tilted stimulus position was held static for 4 min, 40 sec. Results: A compensatory torsional response was found in all subjects and test conditions. No significant difference was found between the different stimuli tilt angles. The torsional response was not maintained but drifted back towards the reference position. Conclusions: Visually induced ocular torsion in response to a static tilted scene is not maintained, but drifts back towards the initial reference position. Higher cognitive functions such as imagination and attention certainly have an influence on the outcome.

KEYWORDS:

• ocular torsion
• visual tilt
• gravity perception
• visual perception
• torsion drift