Visual Influences on Vestibular Adaptation

Purpose

The goal of this study is to determine whether impaired static visual acuity or binocular vision abnormalities affect vestibulo-ocular reflex (VOR) adaptation in adults with and without vestibular hypofunction. The main questions it aims to answer are: - Does reduced static visual acuity change the amount of VOR adaptation achieved during incremental VOR adaptation (IVA) training? - Do binocular vision abnormalities limit VOR adaptation in otherwise healthy adults or in adults with vestibular hypofunction? Because this study includes comparison groups, researchers will compare participants with normal vestibular function and impaired visual acuity versus those with abnormal vestibular function and impaired visual acuity, as well as participants with normal vestibular function and binocular vision abnormalities versus those with abnormal vestibular function and binocular vision abnormalities, to determine whether these visual conditions affect the magnitude of VOR gain change following IVA training.

Conditions

  • Vestibular Hypofunction
  • Binocular Vision Abnormalities
  • Reduced Vision

Eligibility

Eligible Ages
Between 18 Years and 89 Years
Eligible Sex
All
Accepts Healthy Volunteers
No

Inclusion Criteria

For All Participants (All Groups) - Age 18 to 89 years - Able to provide informed consent Group-Specific Inclusion Criteria Group 1: Abnormal Uncorrected Static Visual Acuity (No Vestibular Hypofunction) - Abnormal uncorrected distance visual acuity based on LogMAR thresholds - No clinical evidence of vestibular hypofunction on vHIT Group 2: Abnormal Uncorrected Static Visual Acuity + Vestibular Hypofunction - Abnormal uncorrected distance visual acuity - Vestibular hypofunction confirmed by vHIT (reduced lateral canal gain and corrective saccades) Group 3: Binocular Vision Abnormalities (No Vestibular Hypofunction) - Presence of binocular vision abnormalities (e.g., convergence insufficiency, ocular misalignment) - No vestibular hypofunction on vHIT Group 4: Binocular Vision Abnormalities + Vestibular Hypofunction - Binocular vision abnormalities as above - Vestibular hypofunction confirmed by vHIT

Exclusion Criteria

  • Neurological disorders affecting eye movements or balance (e.g., stroke, multiple sclerosis, Parkinson's disease) - History of traumatic brain injury - Active or unstable medical conditions that could interfere with participation - Uncorrected hearing impairment that prevents following instructions - Inability to perform repeated head impulses due to cervical spine, musculoskeletal, or pain limitations - Current use of medications that significantly affect vestibular function (e.g., vestibular suppressants) - Prior vestibular surgery - Severe visual impairment not correctable with lenses - Pregnancy (due to balance testing requirements) - Any condition that, in the investigator's judgment, would interfere with safe participation

Study Design

Phase
N/A
Study Type
Interventional
Allocation
Randomized
Intervention Model
Crossover Assignment
Intervention Model Description
This study uses a prospective, cross-over observational design in which participants complete two sessions of incremental vestibulo-ocular reflex adaptation (IVA) under different visual conditions. Participants are assigned to one of four groups based on visual status and vestibular function (abnormal visual acuity, binocular vision abnormalities, with or without vestibular hypofunction).
Primary Purpose
Basic Science
Masking
Triple (Participant, Care Provider, Investigator)

Arm Groups

ArmDescriptionAssigned Intervention
Experimental
Group 1: Abnormal Uncorrected Static Visual Acuity (No Vestibular Hypofunction) 		Adults with abnormal uncorrected distance visual acuity and normal vestibular function. This group will be part of Experiment 1. This experiment studies people whose main visual problem is reduced uncorrected distance visual acuity (i.e., blurry vision without glasses/contacts). Experiment 1 tests the effect of blurry vision on VOR adaptation
  • Other: Incremental Vestibulo-Ocular Reflex Adaptation (IVA)
    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.
Experimental
Group 2: Abnormal Uncorrected Static Visual Acuity + Vestibular Hypofunction 		Adults with abnormal uncorrected distance visual acuity and unilateral vestibular hypofunction. This group will be part of Experiment 1. This experiment studies people whose main visual problem is reduced uncorrected distance visual acuity (i.e., blurry vision without glasses/contacts). Experiment 1 tests the effect of blurry vision on VOR adaptation
  • Other: Incremental Vestibulo-Ocular Reflex Adaptation (IVA)
    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.
Experimental
Group 3: Binocular Vision Abnormalities (No Vestibular Hypofunction) 		Adults with binocular vision abnormalities (e.g., convergence insufficiency, ocular misalignment) and normal vestibular function. This group will be part of Experiment 2. This experiment studies people whose main visual problem is how the two eyes work together (e.g., convergence insufficiency, ocular misalignment). Experiment 2 tests the effect of binocular vision dysfunction on VOR adaptation
  • Other: Incremental Vestibulo-Ocular Reflex Adaptation (IVA)
    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.
Experimental
Group 4: Binocular Vision Abnormalities + Vestibular Hypofunction 		Adults with binocular vision abnormalities and unilateral vestibular hypofunction. This group will be part of Experiment 2. This experiment studies people whose main visual problem is how the two eyes work together (e.g., convergence insufficiency, ocular misalignment). Experiment 2 tests the effect of binocular vision dysfunction on VOR adaptation
  • Other: Incremental Vestibulo-Ocular Reflex Adaptation (IVA)
    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.

Recruiting Locations

Emory Ophthalmology Clinics
Atlanta 4180439, Georgia 4197000 30322
Contact:
Jason Peragallo, MD

Dizziness and Balance Center
Atlanta 4180439, Georgia 4197000 30329
Contact:
Colin Grove, PT, DPT, PhD
404-712-8685
colin.r.grove@emory.edu

More Details

Status
Recruiting
Sponsor
Emory University

Study Contact

Colin R Grove, PT,DPT,PhD
(404) 712-8685
colin.riess.grove@emory.edu

Detailed Description

Impairment of vestibular pathways can lead to deficits in balance, gait, and gaze stability. Gaze-stability exercises are a central component of vestibular rehabilitation and have been shown to improve vision during head movement as well as functional mobility in individuals with peripheral or central vestibular dysfunction. Improvements in gaze stability may occur through vestibulo-ocular reflex (VOR) adaptation or through compensatory saccadic eye movements. However, many adults with vestibular hypofunction also present with uncorrected visual acuity deficits or binocular vision abnormalities, such as low vision, convergence insufficiency, or ocular misalignment. These visual conditions are common but understudied in the context of vestibular rehabilitation, and it is not known whether they limit the capacity for VOR adaptation. Incremental vestibulo-ocular reflex adaptation (IVA) is a non-invasive, 15-minute training method that strengthens the VOR by exposing users to a controlled visual error signal. IVA uses a moving laser target whose velocity is programmed as a function of the participant's head movement, producing immediate increases in VOR gain. The method can be customized to provide unilateral, bilateral, or asymmetric adaptation, allowing targeted training for individuals with unilateral or bilateral vestibular deficits. IVA has been studied extensively in adults with vestibular hypofunction, but its effectiveness in individuals with impaired visual acuity or binocular vision abnormalities has not been evaluated. This study will examine whether reduced static visual acuity or binocular vision abnormalities affect the magnitude of VOR adaptation in adults with and without vestibular hypofunction. Two experiments will be conducted using a cross-over design. Experiment 1 will enroll adults with abnormal uncorrected static visual acuity, with and withoutvestibular hypofunction, to compare VOR adaptation with and without vision correction. Experiment 2 will enroll adults with binocular vision abnormalities, with and without vestibular hypofunction, to evaluate VOR adaptation in their best corrected visual state. All participants will complete IVA training during two study visits separated by a washout period.