Visual Influences on Vestibular Adaptation
Effects of Impaired Visual Acuity and Binocular Control Abnormalities (VABC) on Vestibulo-ocular Reflex (VOR) Adaptation in Adults With and Without Vestibular Hypofunction
Emory University
100 participants
Feb 4, 2026
INTERVENTIONAL
Conditions
Summary
The goal of this study is to learn whether a balance-training exercise called incremental vestibulo-ocular reflex adaptation (IVA) is safe and effective for adults with vision impairments, with or without additional vestibular (inner-ear balance) problems. The main questions it aims to answer are: * Does IVA cause only mild, temporary symptoms and no serious adverse events? * Does IVA improve eye-movement reflexes, balance, and walking, and do these improvements differ between people with vision problems alone and those with both vision and vestibular impairments? Researchers will compare adults with vision impairment only to adults who have both vision and vestibular impairments to see whether the groups respond differently to IVA. Participants will: * Complete symptom ratings before and after IVA * Undergo tests of vestibular reflexes (e.g., VOR gain) * Complete balance and walking assessments
Eligibility
Inclusion Criteria15
- For All Participants (All Groups)
- Age 18 to 60 years
- Able to provide informed consent
- Group 1: Abnormal Uncorrected Static Visual Acuity (No Vestibular Hypofunction) Normal peripheral vestibular function
- Group 2: Abnormal Uncorrected Static Visual Acuity + peripheral Vestibular Hypofunction
- Group 3: Binocular Vision Abnormalities (No Vestibular Hypofunction) Normal peripheral vestibular function
- Group 4: Binocular Vision Abnormalities + peripheral Vestibular Hypofunction
- Individuals who have abnormal static visual acuity, a binocular vision abnormality (ocular misalignment, convergence insufficiency), and vestibular loss will be assigned to Group 4.
- The following definitions will be used when determining group placement:
- Abnormal Static Visual Acuity: Uncorrected visual acuity (head is still) ≥0.30 logMAR in both eyes.
- Unilateral Vestibular Hypofunction: 60 ms VOR gain <0.80 unilaterally for the lateral semicircular canal.
- Bilateral Vestibular Hypofunction: 60 ms VOR gain <0.80 bilaterally for the lateral semicircular canals.
- Normal Vestibular Function: 60 ms VOR gain of 0.80 to 1.20 bilaterally for the lateral semicircular canals.
- Convergence Insufficiency: ≥6 cm near point of convergence.
- Ocular Misalignment: ≥4 prism diopters of manifest deviation of the eyes (tropia) on cover/uncover testing.
Exclusion Criteria5
- Diagnosis of fluctuating vestibular disorders (e.g., benign paroxysmal positional vertigo)
- Neurologic conditions (e.g., multiple sclerosis), dementia,
- Alcohol or drug abuse,
- A major psychiatric disorder (e.g., schizophrenia),
- Pain that limits cervical spine range of motion by >50% or that results in an -altered gait pattern.
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Interventions
IVA is delivered using the StableEyes device, which includes a lightweight head-mounted unit with inertial sensors and a micromirror that controls the position of a low-power laser target projected onto a wall. The device adjusts the target's movement based on the participant's head velocity to create a controlled visual error signal that induces vestibulo-ocular reflex (VOR) adaptation. During each session, participants sit about one meter from a blank wall and perform rapid, self-generated head impulses while visually tracking the moving laser target. The target appears at neutral, moves at a fraction of head velocity during each impulse, and briefly disappears before reappearing at center. Each session lasts 15 minutes and includes roughly 150 head impulses in the horizontal or vertical plane. The procedure has been well-tolerated in prior studies with no reported adverse events.
Locations(2)
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NCT07380256