UMIN-ICDS Clinical Trial

Public title

A study on the safety and feasibility of repeated virtual reality-based testing of the perception of vertical in healthy adults, and on the effects of sound and vibration feedback

Acronym

D-SAFE study

Scientific Title

Safety and feasibility of repeated dynamic subjective visual vertical (D-SVV) testing using a head-mounted display in healthy adults: a three-condition, three-period, six-sequence randomized crossover study including exploratory evaluation of the effects of auditory and vibrotactile feedback on spatial orientation measures under visual stimulation

Scientific Title:Acronym

D-SAFE study

Region

Japan

Condition

Healthy adults (participants with any disease are excluded). The intended future clinical application is chronic dizziness, visually induced dizziness, and vestibular hypofunction.

Classification by specialty

Oto-rhino-laryngology

Classification by malignancy

Others

Genomic information

NO

Narrative objectives1

The primary objective is to confirm the safety and the feasibility of repeated dynamic subjective visual vertical (D-SVV) testing using a head-mounted display in healthy adults. The secondary objective is to explore, in comparison with a no-feedback condition, the effects of auditory feedback alone and of combined auditory and vibrotactile feedback during D-SVV on measures of spatial orientation, namely Spatial Visual Susceptibility (SVS) and Postural Visual Susceptibility (PVS). This study is not intended to verify a training effect of sensory feedback.

Basic objectives2

Safety

Basic objectives -Others

Trial characteristics_1

Exploratory

Trial characteristics_2

Developmental phase

Not applicable

Primary outcomes

Two primary outcomes, both evaluated descriptively.
(1) Safety: occurrence and incidence of adverse events, change in the Simulator Sickness Questionnaire (SSQ) score, time course of the brief SSQ score, and frequency of events requiring discontinuation of testing.
(2) Feasibility of repeated testing: completion rate of the 18 D-SVV trials in each condition, completion rate of each period, completion rate of all three periods, discontinuation rate, and dropout rate.

Key secondary outcomes

The principal secondary outcome is the change in SVS and PVS before and after each condition (immediately after minus before). Other secondary outcomes are: change in SVS and PVS at 30 minutes after each condition; within-session time course of rod angle, head angle and brief SSQ score across the 18 repeated D-SVV trials; change in SSQ score before and after each condition and before the 30-minute retest; change in the velocity Romberg ratio and the eyes-closed foam ratio on foam posturography; association between posturographic indices and SVS/PVS; unit trajectory length of body sway during D-SVV (change before and after each condition and at 30 minutes, and within-session time course across the 18 trials); discomfort of mandibular vibratory stimulation and of earphone sound stimulation assessed by a visual analogue scale; and the presence of period and carryover effects.

Study type

Interventional

Basic design

Cross-over

Randomization

Randomized

Randomization unit

Individual

Blinding

Open -no one is blinded

Control

No treatment

Stratification

NO

Dynamic allocation

NO

Institution consideration

Institution is not considered as adjustment factor.

Blocking

YES

Concealment

No. of arms

3

Purpose of intervention

Diagnosis

Type of intervention

Device,equipment

Interventions/Control_1

Condition A (no neurofeedback). Participants wear a head-mounted display (HMD) and undergo 18 trials of dynamic subjective visual vertical (D-SVV) testing while standing on a posturography platform. Each trial lasts approximately 20 seconds, with a 1-minute rest after every 6 trials. The 18 trials comprise combinations of three rotation speeds (10, 20 and 30 degrees/second), two rotation directions (clockwise and counterclockwise) and three starting angles of the rod (-20,-40,-60,+20, +40, +60 degrees). While viewing the rotating visual stimulus, participants adjust the rod to the direction they perceive as vertical. In this condition, neither vibrotactile feedback to the mandible via a tilt perception adjustment device (TPAD) nor auditory feedback via earphones is provided; this condition serves as the control for changes attributable to repeated D-SVV testing itself. In each period, static subjective visual vertical (S-SVV), D-SVV and foam posturography are performed without any feedback before the condition, immediately after the condition, and 30 minutes after the condition. An interval of at least 24 hours is set between periods.

Interventions/Control_2

Condition B (auditory feedback alone). The procedure is the same as in Intervention 1: participants wear an HMD and undergo 18 D-SVV trials while standing on a posturography platform (approximately 20 seconds per trial, with a 1-minute rest after every 6 trials). In this condition, an intermittent tone is presented through commercially available earphones according to the rod angle, only during the 18 D-SVV trials. A higher pitch is presented for a larger absolute rod angle, with a frequency range of 200-2000 Hz and a stepwise correspondence to the angle. The direction of deviation (clockwise or counterclockwise) is distinguished by presenting the tone to the left or right ear. No tone is presented when the absolute rod angle is 0.5 degrees or less. The sound pressure level is limited to 50 dB SPL and adjusted to a level that each participant finds comfortable. The tone is presented only from the start of rod adjustment until the participant confirms the response in each trial. No vibrotactile feedback via TPAD is provided. S-SVV, D-SVV and foam posturography performed before the condition, immediately after the condition, and 30 minutes after the condition are carried out without any feedback.

Interventions/Control_3

Condition C (dual auditory and vibrotactile feedback). The procedure is the same as in Interventions 1 and 2: participants wear an HMD and undergo 18 D-SVV trials while standing on a posturography platform (approximately 20 seconds per trial, with a 1-minute rest after every 6 trials). In addition to auditory feedback identical in specification to Intervention 2 (an intermittent tone of 200-2000 Hz according to the rod angle, a dead band of 0.5 degrees, an upper limit of 50 dB SPL, and left/right ear presentation to indicate the direction of deviation), vibrotactile stimulation is delivered to the mandible via TPAD according to the head angle, only during the 18 D-SVV trials. The vibration frequency is 160 Hz, and the vibration intensity varies with the head tilt angle. The direction of tilt is distinguished by selectively driving the left or right vibrator. Vibrotactile stimulation is presented over the same interval as the auditory feedback, that is, from the start of rod adjustment until the participant confirms the response in each trial. S-SVV, D-SVV and foam posturography performed before the condition, immediately after the condition, and 30 minutes after the condition are carried out without either auditory or vibrotactile feedback.

Interventions/Control_4

Interventions/Control_5

Interventions/Control_6

Interventions/Control_7

Interventions/Control_8

Interventions/Control_9

Interventions/Control_10

Age-lower limit

18

years-old

<=

Age-upper limit

65

years-old

>=

Gender

Male and Female

Key inclusion criteria

1)Men and women aged 18 to 65 years
2)Healthy adults
3)Persons who have received an explanation of the study and have provided written informed consent of their own free will

Key exclusion criteria

1)Persons with a past history of vertigo or balance disorder in whom vestibular hypofunction is suspected
2)Persons with current vertigo, unsteadiness, nausea, headache or similar symptoms that are judged to make D-SVV testing difficult
3)Persons judged by the principal investigator or a sub-investigator to have visual impairment, a history of photosensitive epilepsy, hearing impairment, neurological disease, musculoskeletal disease or any other disease that would affect the evaluation of the study data or safety
4)Persons who are pregnant or who may be pregnant
5)Persons otherwise judged by the principal investigator or a sub-investigator to be unsuitable for participation in this study

Target sample size

36

Name of lead principal investigator

1st name	Go
Middle name
Last name	Sato

Organization

Tokushima University Hospital

Division name

Department of Otorhinolaryngology-Head and Neck Surgery

Zip code

7708503

Address

5-5-5, Suketou-honcho, Tokushima, Japan

TEL

0886337169

Email

go-sato@tokushima-u.ac.jp

Name of contact person

1st name	Go
Middle name
Last name	Sato

Organization

Tokushima University Hospital

Division name

Department of Otorhinolaryngology-Head and Neck Surgery

Zip code

7708503

Address

3-18-15 Kuramoto-cho, Tokushima, Japan

TEL

0886337169

Homepage URL

http://www.toku-oto.umin.jp/

Email

go-sato@tokushima-u.ac.jp

Institute

Tokushima University

Institute

Department

Personal name

Go Sato

Organization

Japan Science and Technology Agency

Organization

Division

Category of Funding Organization

Other

Nationality of Funding Organization

Co-sponsor

Name of secondary funder(s)

Organization

The Ethics Committee of Tokushima University Hospital

Address

2-50-1 Kuramoto-cho, Tokushima 770-8503, Japan

Tel

088-633-7958

Email

brinshoshienk@tokushima-u.ac.jp

Secondary IDs

NO

Study ID_1

Org. issuing International ID_1

Study ID_2

Org. issuing International ID_2

IND to MHLW

Institutions

Date of disclosure of the study information

2026

Year

10

Month

01

Day

URL releasing protocol

Publication of results

Unpublished

URL related to results and publications

Number of participants that the trial has enrolled

Results

Results date posted

Results Delayed

Results Delay Reason

Date of the first journal publication of results

Baseline Characteristics

Participant flow

Adverse events

Outcome measures

Plan to share IPD

IPD sharing Plan description

Recruitment status

Preinitiation

Date of protocol fixation

2026

Year

08

Month

01

Day

Date of IRB

Anticipated trial start date

2027

Year

01

Month

05

Day

Last follow-up date

2030

Year

03

Month

31

Day

Date of closure to data entry

Date trial data considered complete

Date analysis concluded

Other related information

Registered date

2026

Year

09

Month

03

Day

Last modified on

2026

Year

09

Month

03

Day

Link to view the page

Value
https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000071904