Vestibulo-Ocular Responses and Dynamic Visual Acuity During Horizontal Rotation and Translation

Area of Science:

• Neuroscience
• Ophthalmology
• Vestibular System

Background:

• Dynamic visual acuity (DVA) assesses gaze stabilization, influenced by the vestibulo-ocular reflex (VOR), saccades, and visual motion processing.
• DVA is clinically valuable for evaluating patient function and quality of life.
• While DVA during head rotation (rDVA) is studied, DVA during horizontal translation (tDVA) remains unmeasured, limiting understanding of otolith function's impact on visual acuity.

Purpose of the Study:

• To measure and compare DVA during passive head rotation and horizontal translation in healthy subjects.
• To investigate the relationship between VOR gain, retinal slip, and DVA during both rotational and translational head movements.
• To elucidate the specific contribution of otolith function to visual acuity during head translation.

Main Methods:

• Measured DVA during passive head rotations (head impulse test) and horizontal translations in 7 healthy participants.
• Calculated average VOR gain and retinal slip for both movement types.
• Compared DVA, VOR gain, and retinal slip between rotational and translational conditions.

Main Results:

• VOR gain was significantly reduced during translation (position gain 0.21 ± 0.08, velocity gain 0.51 ± 0.16) compared to rotation (position gain 1.05 ± 0.04, velocity gain 0.97 ± 0.07).
• Retinal slip was increased during translation.
• tDVA (0.56 ± 0.09 logMAR) was significantly worse than rDVA (0.32 ± 0.15 logMAR, p=0.02).

Conclusions:

• Reduced VOR gain during head translation directly leads to worse dynamic visual acuity.
• This study introduces tDVA as a novel measure reflecting otolith-dependent visual stabilization.
• Non-oculomotor factors may also influence DVA performance across both rotational and translational head movements.