Smartphone-based Utility of the Vestibulo-ocular Reflex

The goal of this observational study is to evaluate whether a novel smartphone-based (mHealth) application can accurately assess gaze stability and vestibulo-ocular reflex (VOR) function in adults with vestibular dysfunction. This pilot clinical ststudy includes adult participants with and without unilateral peripheral vestibular dysfunction to determine the feasibility of a mobile-based assessment of gaze stabilization.

The main questions it aims to answer are:

1. Can a prototype mHealth application accurately measure outcomes associated with standard dynamic gaze stabilization tests (e.g., static visual acuity, perception time, and maximal head velocity measurements)?
2. How well does a prototype mHealth application identify patients with unilateral peripheral vestibular dysfunction when compared to healthy volunteers?
3. Does a prototype mHealth application differ in identifying patients with unilateral peripheral vestibular dysfunction when compared to a commercially-available computer system that uses a gold-standard head-mounted sensor for gaze stabilization testing (GST)?

Participants will:

Perform the well-established GST protocol using a commercially-available computer system that uses a gold-standard head-mounted sensor Perform the well-established GST protocol a novel mHealth application

The following outcomes will be measured:

1. Standard visual acuity (SVA): The smallest readable target based on the user's best-aided vision
2. A perception time test (PTT): The shortest time a target can be accurately identified
3. A dynamic gaze stability test (GST): The maximal head velocity at which a patient can accurately identify the orientation of a presented visual target

This pilot clinical study will provide evidence to further support the use of mobile technology as a low-cost, accessible alternative for vestibular function assessment, particularly for patients in resource-limited settings.

Background \& Rationale Vestibular dysfunction is a common condition affecting over a third of U.S. adults over the age of 40. It significantly increases the risk of falls, especially in those experiencing dizziness, where the odds of falling are increased 12-fold. Current best practices recommend vestibular rehabilitation, which includes gaze stability exercises designed to improve balance and reduce fall risk. However, many individuals, particularly those relying on home-based therapy or telehealth, face challenges in accessing objective assessments of their vestibulo-ocular reflex (VOR) contribution to gaze stabilization.

As telehealth has expanded rapidly in response to the COVID-19 pandemic, there is an increasing need for remote, real-time VOR teleassessments that can provide clinicians and patients with quantifiable, velocity-specific gaze stability data. While some computer-based remote VOR assessment tools exist, they often suffer from limitations in user satisfaction and accuracy. The Gaze Stabilization Test (GST), developed by Goebel et al., provides clinicians with velocity-specific data associated with the VOR's contribution to gaze stabilization. However, this test is typically performed in a clinical setting with specialized equipment, limiting access for many patients.

This pilot clinical study aims to validate a mHealth application (mVOR) prototype as a low-cost, accessible alternative to traditional VOR assessments. By leveraging the head- and eye-tracking capabilities of modern smartphones, this proof-of-concept prototype seeks to provide a novel, mobile-based framework for measuring visual acuity, head velocity, and gaze estimation in patients undergoing vestibular rehabilitation.

Study Objectives \& Hypothesis

Primary Objectives:

To determine whether a prototype mHealth application can accurately assess static visual acuity, perception time, and maximal head velocity in individuals with unilateral peripheral vestibular dysfunction (UVD).

To compare the accuracy of the mVOR application against a commercially-available, in-office GST system that identifies patients with UVD.

Hypothesis:

The investigators hypothesize that by using the native head and eye-tracking capabilities of smartphones, one can obtain gaze stability (GST) measurements using a mobile platform that provides visual acuity and velocity-specific data comparable to a commercially-available, in-office GST system.

If validated, the mVOR could serve as an platform for effective, low-cost alternatives for telemonitoring vestibular function and enhancing remote rehabilitation programs for individuals with balance disorders.

Anticipated sample size: 50 (25 healthy volunteers and 25 patients with UVD)

Data Analysis

Within-group comparisons:

Paired t-tests or Wilcoxon Signed-Rank tests (depending on data distribution) will compare participants' GST and mVOR scores.

Between-group comparisons:

Independent t-tests or Mann-Whitney U tests will compare UVD vs. healthy volunteer group.

ROC Curve Analysis:

Receiver Operating Characteristic (ROC) curves will assess the accuracy of mVOR vs. computerized GST in distinguishing patients with UVD

Potential Benefits \& Clinical Significance Increased Accessibility: The mVOR app provides an affordable, mobile alternative to in-office based GST system, expanding access to vestibular rehabilitation.

Telehealth \& Home Monitoring: This study could support remote vestibular assessments, particularly for patients in rural or underserved communities.

Clinical Validation: If the mVOR performs comparably to the in-office based GST, it may be integrated into clinical practice as a validated tool for assessing vestibular function.

Eligibility Criteria:
Inclusion Criteria:

* Adults 18 years or older
* Able to provide informed consent
* Normal or corrected-to-normal vision (e.g., with glasses or contact lenses)
* Able to sit upright and follow instructions for the duration of the test (\~2-3 hours)
* No known contraindications to head movement (e.g., musculoskeletal or neurological conditions that prevent safe head rotation)
* For vestibular dysfunction group: Participants must have a diagnosed vestibular disorder (e.g., vestibular hypofunction, vestibular neuritis, Meniere's disease, labyrinthitis, vestibular migraine, or post-concussive dizziness)
* For control group: Participants must be free from diagnosed vestibular disorders and report no history of balance issues, dizziness, or vertigo

Exclusion Criteria:

* Severe visual impairment that cannot be corrected with glasses or contact lenses
* Cognitive impairment or neurological conditions that could interfere with following instructions (e.g., moderate to severe dementia, uncontrolled seizures, severe traumatic brain injury)
* Severe musculoskeletal or orthopedic conditions affecting the neck or cervical spine that prevent safe head movement (e.g., cervical fusion, severe arthritis, neck instability)
* Acute illness or infection at the time of testing (e.g., flu, COVID-19, severe sinus infection that may impact vestibular function)
* Recent vestibular or neurological surgery (\<6 months prior to study participation)
* Severe hearing loss that prevents understanding spoken instructions
* History of stroke or progressive neurological disorders affecting balance or gaze stability (e.g., Parkinson's disease, multiple sclerosis, ALS)
* Use of vestibular suppressants (e.g., meclizine, diazepam, scopolamine) within 24 hours of testing