Subjective visual vertical test: the effect of preset angle and visual background

Shima Iranfar, Leila Jalilvand Karimi, Moslem Shaabani, Marzieh Sharifian Alborzi, Alireza Akbarzadeh Baghban



Background and Aim: Abstract Subjective Visual Vertical (SVV) test estimates mental perception of vertical orientation. Previous researches showed that individuals with normal vestibular function align the SVV line indicator within 2 degrees of true vertical (0 degrees). The aims of this study were to evaluate the effect of preset angle on SVV value in static and dynamic visual background and also to compare the effect of clockwise and counterclockwise rotation of visual background on SVV value.

Material & Method: Fifty normal adults (19 men and 31 women), with ages ranged from 18 to 40 years were asked to set a luminous bar as vertical in six different conditions: two times in static visual background condition and four times in dynamic visual background condition. Synapsys SVV instrument was used in this study.

Results: On one hand, the direction of preset angle had ipsilateral effect on deviation of SVV with static and dynamic background. It means that right preset angle made rightward deviation of SVV and left preset angle made leftward deviation of SVV (P <0.001). On the other hand, the direction of visual background rotation had significant and ipsilateral effect on SVV with dynamic background. It means clockwise rotation made rightward deviation of SVV and counterclockwise rotation made leftward deviation of SVV (P <0.001).

Conclusion: For correct interpretation and precise diagnosis of vestibular disorders using the SVV test within the vestibular test battery, we should consider the effect of preset angle and rotation of visual background on the results.

Key words: subjective visual vertical, static visual background, dynamic visual background, preset angle, orientation of rotation of visual background.

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