AmblyopiaBRAVENCT07803458
Attention-based Binocular Training for Impaired Stereopsis (BRAVE)
A study testing Attention-Guided Dichoptic Visual Search Training and Zero-Disparity Dichoptic Visual Search Task in people with Amblyopia and Strabismus, run by Centre for Eye and Vision Research at 2 sites in Hong Kong.
Trial summary
This study evaluates a novel attention-based binocular visual search training paradigm designed to improve stereopsis (stereo vision) in individuals with impaired binocular vision. Read more about this study
- Who is it for?
- Ages 18 to 39 yearsHealthy volunteers can take part
- Conditions the study is for
- Amblyopia, Strabismus, Anisometropia
- What is being tested?
- Attention-Guided Dichoptic Visual Search Training and Zero-Disparity Dichoptic Visual Search Task
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 56 participants
- Where
- 2 sitesHong Kong
- Study dates
- 1 Nov 2026to 30 Mar 2029
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 39 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Aged 18-39 years (inclusive).
- Deficient or anomalous stereoscopic vision with a stereoacuity >= 70 sec arc or unmeasurable stereoacuity.
- Best corrected visual acuity (BCVA) of < 0.80 logMAR in both eyes, with at least one eye having a visual acuity of <= 0.1 logMAR (uncorrected or corrected-to-normal with glasses or contact lenses).
- Normal colour vision.
- Good general health.
Who cannot join
- Previous history of ocular surgery (except for refractive correction surgery, where appropriate).
- Pre-existing ocular conditions or medications that affect vision or visual function.
- Pre-existing conditions or medications that affect neuropsychological function.
- Presence of strabismus over 10 prism diopters at distance in current refractive correction measured by simultaneous prism and cover test, or large eccentric fixation.
- Previous history of experiencing double vision (diplopia).
- Identified at risk of developing diplopia due to binocular state and/or poor binocular control.
- Inability to comprehend psychophysical test instructions given and/or consent for themselves.
Trial locations and contacts
2 sites in 1 country. Contact the study team or a site near you to ask about taking part.
Hong Kong2 sites
Centre for Eye and Vision Research Limited
Hong Kong, Hong Kong SAR, HKG
Benjamin Thompson, PhD, +852-31699631, ben.thompson@cevr.hk
Tingni Li, PhD, +852-31699631, tingni.li@cevr.hk
The Hong Kong Polytechnic University
Hong Kong, Hong Kong SAR, HKG
Jeffrey TW Leung, PhD, +852-64080394, jeffrey.tw.leung@polyu.edu.hk
Jeffrey TW Leung, PhD
About this study
Official title: Binocular Recovery Through Attention-based Visual Enhancement: A Randomized Controlled Trial (BRAVE Trial)
This study evaluates a novel attention-based binocular visual search training paradigm designed to improve stereopsis (stereo vision) in individuals with impaired binocular vision. Disruptions in balanced binocular input, such as from strabismus or anisometropia, often lead to deficient stereo vision, causing daily visuomotor limitations. While traditional therapies focus on monocular acuity, they frequently fail to restore stereopsis, especially in adults. The investigators propose a unique dichoptic visual search training method that embeds binocular disparity inside an attention-demanding task, encouraging cooperative binocular integration. Participants aged 18-39 with impaired stereopsis will be randomly assigned in a 1:1 ratio to either the active training group (disparity-embeded task) or the active control group (identical task with zero disparity). Both groups complete 5 training sessions over 5-6 weeks. Assessments will occur at baseline, immediately post-training, and at a 12-week follow-up. The primary objective is to determine if the active training group shows significantly greater improvements in local stereoacuity compared to the control group.
- Conditions
- Amblyopia, Strabismus, Anisometropia, Binocular Vision Abnormalities, Binocular Vision Disorder
- Being tested
- Attention-Guided Dichoptic Visual Search Training, Zero-Disparity Dichoptic Visual Search Task
- Keywords
- Stereopsis, Depth Perception, Visual Search, Visual Attention, Dichoptic Training
- Medical subject headings
- Amblyopia, Strabismus, Anisometropia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Attention-Guided Dichoptic Visual Search TrainingBehavioural
A computer-based dichoptic training paradigm in which visual stimuli are presented separately to each eye under balanced interocular contrast . Participants search for conjunction-defined targets across 5 sessions (5 blocks of 192 trials per session). The target stimulus is uniquely paired with crossed binocular disparity to provide depth-based attentional guidance, with target disparity adaptively reduced based on search performance.
Zero-Disparity Dichoptic Visual Search TaskBehavioural
An active control dichoptic task identical in visual stimuli, trial structure (5 sessions; 5 blocks of 192 trials per session), and interocular contrast balancing to the training arm, but presented with zero binocular disparity (all stimuli appear in the same depth plane without depth cues).
| Study group | Role | What they receive |
|---|---|---|
| Active Training Group | Experimental | Participants complete a dichoptic visual search task where the search target is uniquely paired with crossed binocular disparity under balanced interocular contrast. The training consists of 5 sessions (5 blocks of 192 trials per session) over 5-6 weeks with adaptive disparity adjustment. Receives: Behavioral: Attention-Guided Dichoptic Visual Search Training |
| Active Control Group | Active comparator | Participants perform an identical computer-based dichoptic visual search task with the same geometric stimuli, trial structure (5 blocks of 192 trials per session), and interocular contrast balancing, but with zero binocular disparity. Receives: Behavioral: Zero-Disparity Dichoptic Visual Search Task |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Local Stereoacuity
Measured using the Randot Stereotest - Circles test (graded disparities from 400 to 20 arcsec, 10 levels) under standardized lighting at 40 cm. The score is recorded as the finest disparity correctly identified (in log arcseconds). Nil stereopsis is assigned 3000 arcsec (3.477 log arcsec). The primary metric is the between-group difference in the change score.
Measured: Baseline (T0) and Immediately Post-Training (T1, within 7 days after Session 5, approximately 5-6 weeks from baseline).
Secondary outcomes (13)
Retention of Local Stereoacuity Gains
Measured using the Randot Stereotest - Circles test under crossed disparity (log10 arcsec; nil stereopsis assigned 3000 arcsec) to evaluate long-term maintenance of training effects
Measured: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Uncrossed Local Stereoacuity
Measured using the Randot Stereotest - Circles test with the test booklet rotated 180 degrees (log10 arcsec; nil stereopsis assigned 3000 arcsec).
Measured: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Global Stereoacuity
Measured with the Randot Preschool Stereotest (random-dot stereograms, 800 to 40 arcsec, 6 levels) under both crossed and uncrossed disparity conditions (log10 arcsec; nil stereopsis assigned 3000 arcsec).
Measured: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Laboratory-Based Stereoacuity Threshold
Psychophysical stereoacuity threshold (75% threshold in log10 arcsec) measured using a 4-alternative forced-choice staircase ring test administered dichoptically.
Measured: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Best-Corrected Visual Acuity (BCVA)
Monocular (affected/dominant eyes) and binocular distance visual acuity measured using an electronic ETDRS logMAR chart at 4 meters (recorded in logMAR units).
Measured: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Interocular Suppression Status
Binocular status classified into categorical states (fusion, suppression, or diplopia) using the Worth 4-dot test at near (40 cm) and distance (3 m).
Measured: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Interocular Suppression Strength (Contrast Balance Ratio)
Effective suppression depth quantified by the interocular contrast ratio at the perceptual balance point measured via a dichoptic letter-polarity task.
Measured: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Visual Evoked Potentials (VEPs)
Peak latencies (ms) and amplitudes (μV) of the transient pattern-reversal VEP N75-P100-N135 complex across high-contrast and isoluminant red-green conditions, alongside harmonic amplitudes/phases (2F, 4F) from steady-state VEPs, recorded via a 64-channel EEG system.
Measured: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Electrophysiological Marker of Attentional Selection (N2pc Component)
Mean amplitude (μV) of the posterior contralateral-minus-ipsilateral difference wave (N2pc) extracted across predefined parieto-occipital electrodes (P7, PO7, P8, PO8) during a modified spatial cueing task.
Measured: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Behavioral Selective Attention
Spatial cueing effects on mean reaction time (ms) and response accuracy (%) derived from the modified spatial cueing task.
Measured: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Visual Search Efficiency
Visual search slope (reaction time as a function of set size, in ms/item) measured from a 192-trial zero-disparity dichoptic visual search task.
Measured: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Visuomotor Coordination Completion Time and Kinematic Parameters
Visuomotor dexterity and kinematic performance are assessed using the Grooved Pegboard Test separately for dominant and non-dominant hands. Hand movements during the task are video recorded for detailed kinematic tracking. The primary quantitative metric for this outcome is the total completion time (in seconds) required to successfully place all 25 grooved pegs (shorter duration indicates better motor speed and coordination). Secondary kinematic metrics extracted from video analyses include mean peg-insertion duration (seconds), inter-peg temporal variability across the 25 trials (coefficient of variation, CV), and total drop/error counts.
Measured: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Quality of Life Scores
Domain scores assessed via the World Health Organization Quality of Life Instrument-Short Form (WHO QoL-BREF) and the Amblyopia and Strabismus Questionnaire (A\&SQ). Higher scores indicate superior functional visual ability and quality of life. For both questionnaires, domain and composite scores are linearly transformed to a standardized 0 to 100 scale, where higher scores represent superior functional visual ability, fewer daily limitations, and better overall quality of life.
Measured: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted3 Sep 2026
- Study start1 Nov 2026 (estimated)
- Primary completion31 Dec 2028 (estimated)
- Study completion30 Mar 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for AmblyopiaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 56 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Centre for Eye and Vision Research
- Sponsor type
- University, hospital or other
- Collaborators
- The Hong Kong Polytechnic University, University of Waterloo
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07803458
- Sponsor's protocol ID
- RP1.4_BRAVE
- Acronym
- BRAVE
- Status last verified
- Aug 2026
- First submitted
- 31 Aug 2026
- Last updated
- 3 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Anonymized data will be shared on request.
Study at a glance
From the registry record, last updated by the sponsor on 3 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Binocular Recovery Through Attention-based Visual Enhancement: A Randomized Controlled Trial (BRAVE Trial)
- ClinicalTrials.gov ID
- NCT07803458
- Acronym / sponsor ID
- BRAVE / RP1.4_BRAVE
- Conditions
- Amblyopia, Strabismus, Anisometropia, Binocular Vision Abnormalities, Binocular Vision Disorder
- Keywords
- Stereopsis, Depth Perception, Visual Search, Visual Attention, Dichoptic Training
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 56 participants (estimated)
- Lead sponsor
- Centre for Eye and Vision ResearchUniversity, hospital or other
- Collaborators
- The Hong Kong Polytechnic University, University of Waterloo
- Study start
- 1 Nov 2026 (estimated)
- Primary completion
- 31 Dec 2028 (estimated)
- Study completion
- 30 Mar 2029 (estimated)
- First posted
- 3 Sep 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study evaluates a novel attention-based binocular visual search training paradigm designed to improve stereopsis (stereo vision) in individuals with impaired binocular vision. Disruptions in balanced binocular input, such as from strabismus or anisometropia, often lead to deficient stereo vision, causing daily visuomotor limitations. While traditional therapies focus on monocular acuity, they frequently fail to restore stereopsis, especially in adults. The investigators propose a unique dichoptic visual search training method that embeds binocular disparity inside an attention-demanding task, encouraging cooperative binocular integration. Participants aged 18-39 with impaired stereopsis will be randomly assigned in a 1:1 ratio to either the active training group (disparity-embeded task) or the active control group (identical task with zero disparity). Both groups complete 5 training sessions over 5-6 weeks. Assessments will occur at baseline, immediately post-training, and at a 12-week follow-up. The primary objective is to determine if the active training group shows significantly greater improvements in local stereoacuity compared to the control group.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Active Training Group | Experimental | Behavioral: Attention-Guided Dichoptic Visual Search TrainingParticipants complete a dichoptic visual search task where the search target is uniquely paired with crossed binocular disparity under balanced interocular contrast. The training consists of 5 sessions (5 blocks of 192 trials per session) over 5-6 weeks with adaptive disparity adjustment. |
| Active Control Group | Active comparator | Behavioral: Zero-Disparity Dichoptic Visual Search TaskParticipants perform an identical computer-based dichoptic visual search task with the same geometric stimuli, trial structure (5 blocks of 192 trials per session), and interocular contrast balancing, but with zero binocular disparity. |
Who may qualify
- Ages
- 18 to 39 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Aged 18-39 years (inclusive).
- Deficient or anomalous stereoscopic vision with a stereoacuity >= 70 sec arc or unmeasurable stereoacuity.
- Best corrected visual acuity (BCVA) of < 0.80 logMAR in both eyes, with at least one eye having a visual acuity of <= 0.1 logMAR (uncorrected or corrected-to-normal with glasses or contact lenses).
- Normal colour vision.
- Good general health.
Key exclusion criteria (7 listed)
- Previous history of ocular surgery (except for refractive correction surgery, where appropriate).
- Pre-existing ocular conditions or medications that affect vision or visual function.
- Pre-existing conditions or medications that affect neuropsychological function.
- Presence of strabismus over 10 prism diopters at distance in current refractive correction measured by simultaneous prism and cover test, or large eccentric fixation.
- Previous history of experiencing double vision (diplopia).
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Attention-Guided Dichoptic Visual Search TrainingA computer-based dichoptic training paradigm in which visual stimuli are presented separately to each eye under balanced interocular contrast . Participants search for conjunction-defined targets across 5 sessions (5 blocks of 192 trials per session). The target stimulus is uniquely paired with crossed binocular disparity to provide depth-based attentional guidance, with target disparity adaptively reduced based on search performance. | Behavioural | Active Training Group |
| Zero-Disparity Dichoptic Visual Search TaskAn active control dichoptic task identical in visual stimuli, trial structure (5 sessions; 5 blocks of 192 trials per session), and interocular contrast balancing to the training arm, but presented with zero binocular disparity (all stimuli appear in the same depth plane without depth cues). | Behavioural | Active Control Group |
Primary outcome
Change in Local Stereoacuity
Time frame: Baseline (T0) and Immediately Post-Training (T1, within 7 days after Session 5, approximately 5-6 weeks from baseline).
Measured using the Randot Stereotest - Circles test (graded disparities from 400 to 20 arcsec, 10 levels) under standardized lighting at 40 cm. The score is recorded as the finest disparity correctly identified (in log arcseconds). Nil stereopsis is assigned 3000 arcsec (3.477 log arcsec). The primary metric is the between-group difference in the change score.
13 secondary outcomes
Retention of Local Stereoacuity Gains
Time frame: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Uncrossed Local Stereoacuity
Time frame: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Global Stereoacuity
Time frame: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Laboratory-Based Stereoacuity Threshold
Time frame: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Best-Corrected Visual Acuity (BCVA)
Time frame: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Interocular Suppression Status
Time frame: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Interocular Suppression Strength (Contrast Balance Ratio)
Time frame: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Visual Evoked Potentials (VEPs)
Time frame: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Electrophysiological Marker of Attentional Selection (N2pc Component)
Time frame: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Behavioral Selective Attention
Time frame: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Visual Search Efficiency
Time frame: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Visuomotor Coordination Completion Time and Kinematic Parameters
Time frame: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Change in Quality of Life Scores
Time frame: Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 3 Sep 2026.
- Individual participant dataSharing planned: Yes. Anonymized data will be shared on request.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Attention-Guided Dichoptic Visual Search Training and Zero-Disparity Dichoptic Visual Search Task in people with Amblyopia and Strabismus, run by Centre for Eye and Vision Research at 2 sites in Hong Kong.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 3 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in Hong Kong. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Jeffrey TW Leung, PhD (+852-64080394, jeffrey.tw.leung@polyu.edu.hk), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Local Stereoacuity (time frame: Baseline (T0) and Immediately Post-Training (T1, within 7 days after Session 5, approximately 5-6 weeks from baseline).). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 3 Sep 2026.