Attention-based Binocular Training for Impaired Stereopsis (BRAVE)
Trial statusNot yet recruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age18-39
SponsorCentre for Eye and Vision Research
About this 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.
Eligibility criteria
This trial accepts healthy volunteersQualifiers
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.
Disqualifiers
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.
Trial design
Design model
Parallel
Treatments tested in this trial
Attention-Guided Dichoptic Visual Search Training
BehavioralA 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 Task
BehavioralAn 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).
Treatment groups
56 Participants
are divided into 2 treatment groupsGroup A: Active Training GroupExperimental treatment 1 intervention
Group B: Active Control GroupActive comparator 1 intervention
Trial outcomes
Primary outcomes
1
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.
Time frame
Baseline (T0) and Immediately Post-Training (T1, within 7 days after Session 5, approximately 5-6 weeks from baseline).Secondary outcomes
1
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
Time frame
Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).2
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).
Time frame
Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).3
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).
Time frame
Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).4
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.
Time frame
Baseline (T0), Immediately Post-Training (T1), and 12-Week Follow-Up (T2).Sponsors and contacts
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Centre for Eye and Vision Research
Lead sponsor
The Hong Kong Polytechnic University
Collaborator
University of Waterloo
Collaborator
Source ClinicalTrials.gov
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