Binocular Alignment Changes Between Sitting and Supine Positions in Patients with Dizziness

Area of Science:

• Neuroscience
• Ophthalmology
• Vestibular System

Background:

• Ocular misalignment, both vertical and torsional, can stem from mild traumatic brain injury or inner ear issues.
• These misalignments may fluctuate with head position, impacting visual perception and balance.

Purpose of the Study:

• To evaluate differences in a behavioral measure of binocular alignment in upright versus supine head positions.
• To compare ocular alignment in veterans with dizziness, civilians with vestibular schwannoma resection, and healthy controls.

Main Methods:

• The torsional and vertical alignment nulling (TAN, VAN) task was used to measure ocular perception of alignment.
• Participants included 52 veterans with dizziness (38 with TBI), 41 civilians post-vestibular schwannoma resection (UVD), and 33 healthy controls.
• Generalized estimating equations compared alignment scores between groups and across head positions (upright and supine).

Main Results:

• Torsional misalignment (TAN) was significantly greater in veterans with dizziness and UVD patients compared to controls.
• Vertical misalignment (VAN) worsened significantly when moving from upright to supine head position, but showed no group differences.
• Head position had minimal effect on torsional and vertical misalignment measures.

Conclusions:

• Torsional misalignments are more prevalent in veterans with dizziness and UVD patients, even without reported diplopia.
• Altered tolerance for roll misalignment might be characteristic of dizziness patients, or perceptual misalignment could be a cause of dizziness.
• This behavioral measure may serve as a proxy for assessing otolith function differences in veterans experiencing dizziness.