Horizontal Vestibulo-Ocular Reflex Gain Measures During Convergence Using a Monocular Video Technique

Area of Science:

• Ophthalmology
• Neuroscience
• Vestibular System Physiology

Background:

• Vestibulo-ocular reflex (VOR) measurements during convergence are crucial for assessing peripheral vestibular organ function.
• Existing clinical monocular video-oculography (VOG) systems can be utilized for these measurements.

Purpose of the Study:

• To develop and validate a monocular VOG technique for accurate measurement of convergence angle before head movements.
• To assess the feasibility of using standard VOG systems for VOR and convergence analysis.

Main Methods:

• Recorded binocular eye movements during active/passive horizontal head impulses with near/far targets.
• Calculated convergence angles and VOR gains using both monocular and binocular VOG methods.
• Compared VOG-derived measurements with a geometric model.

Main Results:

• The monocular VOG technique yielded convergence angle and VOR gain values with approximately 10% difference compared to binocular calculations.
• Demonstrated the reliability of the monocular approach in measuring VOR and convergence.

Conclusions:

• The developed monocular VOG technique is clinically implementable with existing, unmodified commercial VOG systems.
• This method enables reliable measurement of near-viewing horizontal angular VOR during head impulse tests.
• Facilitates translational VOR assessment and clinical diagnosis of convergence insufficiency.