Visual Influences on Vestibular Adaptation

Emory University

Status: Enrolling

Conditions: Binocular Vision Abnormalities; Vestibular Hypofunction; Reduced Vision

Treatments: Other: Incremental Vestibulo-Ocular Reflex Adaptation (IVA)

Study type: Interventional

Funder types: Other

Identifiers

NCT07380256

2025P012555

Details and patient eligibility

About

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.

Full 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.

Enrollment: 100 estimated patients

Sex: All

Ages: 18 to 89 years old

Volunteers: No Healthy Volunteers

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

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Triple Blind

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100 participants in 4 patient groups

Group 1: Abnormal Uncorrected Static Visual Acuity (No Vestibular Hypofunction)

Experimental group

Description:

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

Treatment:

Other: Incremental Vestibulo-Ocular Reflex Adaptation (IVA)

Group 2: Abnormal Uncorrected Static Visual Acuity + Vestibular Hypofunction

Experimental group

Description:

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

Treatment:

Other: Incremental Vestibulo-Ocular Reflex Adaptation (IVA)

Group 3: Binocular Vision Abnormalities (No Vestibular Hypofunction)

Experimental group

Description:

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

Treatment:

Other: Incremental Vestibulo-Ocular Reflex Adaptation (IVA)

Group 4: Binocular Vision Abnormalities + Vestibular Hypofunction

Experimental group

Description:

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

Treatment:

Other: Incremental Vestibulo-Ocular Reflex Adaptation (IVA)