Attention-based Binocular Training for Impaired Stereopsis (BRAVE)

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. 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

Interventions

BEHAVIORAL

Attention-Guided Dichoptic Visual Search Training

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.

BEHAVIORAL

Zero-Disparity Dichoptic Visual Search Task

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).

Sponsors & Collaborators

• The Hong Kong Polytechnic University

  collaborator OTHER

• University of Waterloo

  collaborator OTHER

• Centre for Eye and Vision Research

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

SINGLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

39 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2026-11-01

Primary Completion

2028-12-31

Completion

2029-03-30

Countries

• Hong Kong

Study Locations