Effects of Impaired Visual Acuity and Binocular Control Abnormalities (VABC) on Vestibulo-ocular Reflex (VOR) Adaptation in Adults With and Without Vestibular Hypofunction
试验速览
- 阶段
- 不适用
- 状态
- 招募中
- 入组人数
- 100
- 试验地点
- 2
- 主要终点
- Change in Vestibulo-Ocular Reflex (VOR) Gain
研究概览
简要总结
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
详细描述
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.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Crossover
- 主要目的
- Basic Science
- 盲法
- Double (Participant, Investigator)
入排标准
- 年龄范围
- 18 Years 至 60 Years（Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •For All Participants (All Groups)
- •Age 18 to 60 years
- •Able to provide informed consent
- •Group-Specific Inclusion Criteria:
- •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
- •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.
排除标准
- •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.
研究组 & 干预措施
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
干预措施: StableEyes: Incremental Vestibulo-Ocular Reflex Adaptation (IVA) (Device)
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
干预措施: StableEyes: Incremental Vestibulo-Ocular Reflex Adaptation (IVA) (Device)
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
干预措施: StableEyes: Incremental Vestibulo-Ocular Reflex Adaptation (IVA) (Device)
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
干预措施: StableEyes: Incremental Vestibulo-Ocular Reflex Adaptation (IVA) (Device)
结局指标
主要结局
Change in Vestibulo-Ocular Reflex (VOR) Gain
时间窗: Baseline (visit 1) (before and after after IVA intervention), Visit 2 (2-10 days from baseline) (before and after IVA intervention)
VOR gain will be measured using the video head impulse test (vHIT). Gain is calculated as eye velocity divided by head velocity during high-acceleration, moderate velocity, small amplitude head rotations in the plane of the semicircular canals. This outcome quantifies the strength of the vestibulo-ocular reflex, with higher gain values indicating stronger VOR responses, with normal gain = 0.8 to 1.2. The change in VOR gain from before to after training will be used to assess VOR adaptation. IVA: Incremental Vestibulo-Ocular Reflex Adaptation
次要结局
- Change in Modified Clinical Test of Sensory Interaction in Balance (mCTSIB)(Baseline (visit 1) (before and after after IVA intervention), Visit 2 (2-10 days from baseline) (before and after IVA intervention))
- Change in Gait Disorientation Test (GDT)(Baseline (visit 1) (before and after after IVA intervention), Visit 2 (2-10 days from baseline) (before and after IVA intervention))
- Symptom Severity During IVA (Verbal Analog Scales)(Baseline (visit 1) (before and after after IVA intervention), Visit 2 (2-10 days from baseline) (before and after IVA intervention))
研究者
Colin R. Grove
Assistant Professor
Emory University