Optokinetic Nystagmus
Conditions
Keywords
eye movements, electronystagmography, nystagmus, electrooculogram, vestibular assessment
Brief summary
Clinical investigation of a medical device (CAVA) for recording eye movements. Healthy volunteers will wear the device for 23 hours a day, for 30 days. On 8 separate days of the trial they will induce optokinetic nystagmus (a normal reflex in response to full-field motion) by watching a short video of less than 1 minute in duration. The data will be analysed offline by a scientist, who will attempt to identify the dates that the nystagmus was induced.
Detailed description
Dizziness is a common condition that is responsible for a significant degree of material morbidity and burden on the National Health Service. There are multiple causes of dizziness, and these originate from pathologies affecting a large variety of different organ systems. Dizziness is usually episodic and short-lived, so when a patient presents to their health care provider, examination is often normal. As such, diagnosis is challenging and patients often experience significant delay in receiving a diagnosis. The investigators have developed a prototype device for monitoring dizziness and have tested it in a small group of volunteers. The results showed that their device is capable of accurately, precisely and reliably identifying periods of dizziness over a short period of time. Independent market research has confirmed that their device could meet the required clinical need, would be desired by clinicians, and that there is no equivalent solution currently available. The investigators have received an award from the Medical Research Council to trial their device in a large cohort of healthy volunteers. Once completed, they will be positioned well to test their device in a cohort of patients with a defined dizziness syndrome, before further testing their device in a more diverse patient population. Once validated, developed and brought to market, the device would provide early diagnosis and accurate treatment for a significant proportion of the patient population. This would save the National Health Service money by reducing multiple visits to General Practitioner clinics, reducing referrals to multiple specialist clinics, and reducing treatment required from falls and other conditions associated with dizziness. The overall aim of this trial is to test a fully evolved device for the continuous recording of eye movements over a prolonged period of time. For the purpose of this study, the monitoring period is 23 hours a day, for 30 days. The device is composed of two components: a bespoke single-use sensor array that adheres to the participant's face, and a small reusable module that contains a battery, microcomputer, data storage facility, battery and connection port. The investigators intend to confirm that the device will be able to capture any occurrence, of a minimum period of thirty seconds, of artificially induced nystagmus, within a 24-hour period of time. Each participant will be provided with the device and enough single-use electrode arrays to allow the array to be changed every 24 hours, for thirty days. Participants will be allowed to remove the sensor array for up to 60 minutes each day to allow them to wash and/or shower. On eight of the thirty days for which they wear the array, each participant will be required to induce physiological nystagmus by viewing optokinetic video footage. The footage will be viewed on a portable screen (of a deactivated mobile phone) inside a Virtual Reality headset. These will be issued to the participants at the beginning of the trial. Participants will undertake the procedure whilst stationary for the first four days, and whilst walking gently on the spot for the remaining four days. The identity of these days will not be revealed to the blinded investigator who will later analyse the data. At the end of the thirty-day trial, the sensitivity and specificity of the device will be determined by assessing whether the data can be used to correctly identify the dates that participants induced nystagmus.
Interventions
DEVICECAVA
prototype device for monitoring dizziness
Sponsors
Julie Dawson
University of East Anglia
Medical Research Council
Study design
Observational model
COHORT
Time perspective
OTHER
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
* Adults aged 18 and over * Able to commit to 30 days of continuous wear of the trial device as per the study plan * Own a telephone
Exclusion criteria
* Potential participants who have a history of dermatological disease or damage around the forehead * Potential participants who have an allergy to plasters and/or medical adhesives * History of dizziness, vertigo, balance disorders, or syncope * History of hypertension or cardiac problems (uncontrolled, acute or de-compensated phase) * History of ear disease, or previous ear surgery * History of psychotic/neurotic disorders or epilepsy * History of eye disease, or previous eye surgery * Unable to follow the testing protocol
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Sensitivity and Specificity of a Computer Algorithm to Detect Artificially Induced Nystagmus | 30 days | Dates containing nystagmus. Of the \ 450 days' worth of data captured during the study, 120 will contain artificially induced nystagmus. A computer algorithm has been developed at the University of East Anglia for detecting nystagmus. The key measurements are the sensitivity and specificity of the algorithm's results when applied to data captured during the trial. This measurement will be assessed post-trial. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Compliance With the Device. | 30 days | 1 - There is a minimum of 80% compliance with wearing the device for each single day of the trial for a minimum of 80% of participants. 2 There is a minimum of 80% compliance with wearing the device for the entirety of the 30-day trial for a minimum of 80% of participants. |
| Data Usefulness | 30 days | The device provides less than 5% non-useful data for each participant. We will report the percentage of non-useful data (corrupted or flat-line data) that is captured for each participant. |
| Event Marker Functioning | 30 days | During a return visit, the event marker on each device will be pressed and the time noted. Post-trial, the data on the device will be examined to confirm that an event was recorded on the correct date. This will produce either a positive or negative outcome, depending on whether the event marker button press is present in the data or not. The percentage of identifiable button presses across all devices will be reported. |
| Time Stamp Accuracy | 30 days | The difference will be calculated between the time noted by the research team and the time logged by the device when the event marker was activated. The time difference (in hh:mm:ss) will be calculated across all devices and we will report the average and standard deviation of the clock drift. |
| Accelerometer Functioning | 30 days | Participants will perform a number of head movements and the device data will be examined visually to confirm that they can be identified. This will produce either a positive or negative outcome for each head movement, depending on whether the movement is visible in the data or not. The proportion of successfully identified head movements will be reported. |
| Post-trial Participant Questionnaire. | 30 days | A 2-page questionnaire producing qualitative and quantitative data. Participants rate different aspects of their experiences with the device using a sliding scale and have the opportunity to write more detailed descriptions. |
| Accuracy of Nystagmus Onset Time | 1 hour | Also from the data captured during caloric testing, the start time of nystagmus will be identified from both the VNG data and data captured by the CAVA device. The time difference (in mm:ss) will be calculated between the two data sources and the mean time difference will be reported. |
| Accuracy of Nystagmus Finishing Time | 1 hour | Also from the data captured during caloric testing, the finishing time of nystagmus will be identified from both the VNG data and data captured by the CAVA device. The time difference (in mm:ss) will be calculated between the two data sources and the mean time difference will be reported. |
| Accuracy of Nystagmus Peak Time | 1 hour | Also from the data captured during caloric testing, the time at which the nystagmus reaches its maximum slow phase velocity will be calculated from the VNG data and the data captured by the CAVA device. The time difference (in mm:ss) will be calculated between the two data sources and the mean time difference will be reported. |
| Accuracy of Nystagmus Frequency | 1 hour | Also from the data captured during caloric testing, the number of beats will be counted during the period identified as the nystagmus peak time. This will be calculated for both the VNG data and the data captured by the CAVA device. From the number of beats and time duration examined, the frequency of the nystagmus will be determined. The difference between the two systems will be calculated and the mean difference will be reported. The Unit of Measure will be Hz (number of beats per second). |
| Data Drop-outs | 30 days | The device provides less 5 drop-outs for each single day of the trial for each participant. We will report the maximum number of drop-outs (periods when the device stopped logging) per participant, per day. |
| Accuracy of Nystagmus Beat Direction | 1 hour | Participants will undergo caloric testing at the end of the trial, during which they will wear conventional Videonystagmography (VNG) goggles as well as the CAVA device. The beat direction (whether the fast phase of the nystagmus is towards the left or right ear) will be determined from both sources of data during the period of nystagmus captured. This will produce either a positive or negative outcome, depending on whether the beat direction matches in both data sources. The proportion of matches will be reported. |
Countries
United Kingdom
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Healthy Volunteers All trial participants are within this group. All trial participants will wear the CAVA device for up to 23 hours a day, for 30 days.
CAVA: prototype device for monitoring dizziness | 18 |
| Total | 18 |
Baseline characteristics
| Characteristic | Healthy Volunteers | — |
|---|---|---|
| Age, Categorical <=18 years | 0 Participants | — |
| Age, Categorical >=65 years | 0 Participants | — |
| Age, Categorical Between 18 and 65 years | 18 Participants | — |
| Healthy Volunteers | 18 Participants | — |
| Race and Ethnicity Not Collected | — | — Participants |
| Sex: Female, Male Female | 12 Participants | — |
| Sex: Female, Male Male | 6 Participants | — |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | 0 / 18 |
| other Total, other adverse events | 10 / 18 |
| serious Total, serious adverse events | 0 / 18 |
Outcome results
Primary
Sensitivity and Specificity of a Computer Algorithm to Detect Artificially Induced Nystagmus
Dates containing nystagmus. Of the \ 450 days' worth of data captured during the study, 120 will contain artificially induced nystagmus. A computer algorithm has been developed at the University of East Anglia for detecting nystagmus. The key measurements are the sensitivity and specificity of the algorithm's results when applied to data captured during the trial. This measurement will be assessed post-trial.
Time frame: 30 days
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| Healthy Volunteers | Sensitivity and Specificity of a Computer Algorithm to Detect Artificially Induced Nystagmus | Sensitivity | 99.1 Percent |
| Healthy Volunteers | Sensitivity and Specificity of a Computer Algorithm to Detect Artificially Induced Nystagmus | Specificity | 98.6 Percent |
Secondary
Accelerometer Functioning
Participants will perform a number of head movements and the device data will be examined visually to confirm that they can be identified. This will produce either a positive or negative outcome for each head movement, depending on whether the movement is visible in the data or not. The proportion of successfully identified head movements will be reported.
Time frame: 30 days
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| Healthy Volunteers | Accelerometer Functioning | Slow head turning | 97 percentage of movements identified |
| Healthy Volunteers | Accelerometer Functioning | Slow head nodding | 100 percentage of movements identified |
| Healthy Volunteers | Accelerometer Functioning | Slow head tilting | 100 percentage of movements identified |
| Healthy Volunteers | Accelerometer Functioning | Fast head turning | 93 percentage of movements identified |
| Healthy Volunteers | Accelerometer Functioning | Fast head nodding | 100 percentage of movements identified |
| Healthy Volunteers | Accelerometer Functioning | Fast head tilting | 97 percentage of movements identified |
Secondary
Accuracy of Nystagmus Beat Direction
Participants will undergo caloric testing at the end of the trial, during which they will wear conventional Videonystagmography (VNG) goggles as well as the CAVA device. The beat direction (whether the fast phase of the nystagmus is towards the left or right ear) will be determined from both sources of data during the period of nystagmus captured. This will produce either a positive or negative outcome, depending on whether the beat direction matches in both data sources. The proportion of matches will be reported.
Time frame: 1 hour
Secondary
Accuracy of Nystagmus Finishing Time
Also from the data captured during caloric testing, the finishing time of nystagmus will be identified from both the VNG data and data captured by the CAVA device. The time difference (in mm:ss) will be calculated between the two data sources and the mean time difference will be reported.
Time frame: 1 hour
Secondary
Accuracy of Nystagmus Frequency
Also from the data captured during caloric testing, the number of beats will be counted during the period identified as the nystagmus peak time. This will be calculated for both the VNG data and the data captured by the CAVA device. From the number of beats and time duration examined, the frequency of the nystagmus will be determined. The difference between the two systems will be calculated and the mean difference will be reported. The Unit of Measure will be Hz (number of beats per second).
Time frame: 1 hour
Secondary
Accuracy of Nystagmus Onset Time
Also from the data captured during caloric testing, the start time of nystagmus will be identified from both the VNG data and data captured by the CAVA device. The time difference (in mm:ss) will be calculated between the two data sources and the mean time difference will be reported.
Time frame: 1 hour
Secondary
Accuracy of Nystagmus Peak Time
Also from the data captured during caloric testing, the time at which the nystagmus reaches its maximum slow phase velocity will be calculated from the VNG data and the data captured by the CAVA device. The time difference (in mm:ss) will be calculated between the two data sources and the mean time difference will be reported.
Time frame: 1 hour
Secondary
Compliance With the Device.
1 - There is a minimum of 80% compliance with wearing the device for each single day of the trial for a minimum of 80% of participants. 2 There is a minimum of 80% compliance with wearing the device for the entirety of the 30-day trial for a minimum of 80% of participants.
Time frame: 30 days
Population: For the 30-day trial compliance, the number of participants differs as not all participants completed the trial in full.
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| Healthy Volunteers | Compliance With the Device. | Daily compliance | 82 percentage of participants |
| Healthy Volunteers | Compliance With the Device. | 30-day compliance | 100 percentage of participants |
Secondary
Data Drop-outs
The device provides less 60 drop-outs for the entirety of the 30-day trial across all participants. We will report the total number of drop-outs that occurred over the entire trial, across all participants.
Time frame: 30 days
Population: Healthy volunteers
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Healthy Volunteers | Data Drop-outs | 4 Total number of drop outs |
Secondary
Data Drop-outs
The device provides less 5 drop-outs for each single day of the trial for each participant. We will report the maximum number of drop-outs (periods when the device stopped logging) per participant, per day.
Time frame: 30 days
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Healthy Volunteers | Data Drop-outs | 0.2353 Number of drop outs | Standard Deviation 0.4372 |
Secondary
Data Usefulness
The device provides less than 5% non-useful data for each participant. We will report the percentage of non-useful data (corrupted or flat-line data) that is captured for each participant.
Time frame: 30 days
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Healthy Volunteers | Data Usefulness | 0 Percentage of non-useful data | Standard Deviation 0 |
Secondary
Data Usefulness
The device provides less than 5% non-useful data for the entirety of the 30-day trial across all participants. We will report the percentage of non-useful data (corrupted or flat-line data) that is captured over the entire trial, across all participants.
Time frame: 30 days
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Healthy Volunteers | Data Usefulness | 0 percentage of non-useful data |
Secondary
Event Marker Functioning
During a return visit, the event marker on each device will be pressed and the time noted. Post-trial, the data on the device will be examined to confirm that an event was recorded on the correct date. This will produce either a positive or negative outcome, depending on whether the event marker button press is present in the data or not. The percentage of identifiable button presses across all devices will be reported.
Time frame: 30 days
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Healthy Volunteers | Event Marker Functioning | 100 percentage of button presses identified |
Secondary
Post-trial Participant Questionnaire.
A 2-page questionnaire producing qualitative and quantitative data. Participants rate different aspects of their experiences with the device using a sliding scale and have the opportunity to write more detailed descriptions.
Time frame: 30 days
Secondary
Time Stamp Accuracy
The difference will be calculated between the time noted by the research team and the time logged by the device when the event marker was activated. The time difference (in hh:mm:ss) will be calculated across all devices and we will report the average and standard deviation of the clock drift.
Time frame: 30 days
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Healthy Volunteers | Time Stamp Accuracy | -17.49 minutes per day | Standard Deviation 1.47 |