Augmented Reality-Based Binocular Therapy for Visual Rehabilitation in Adults With Amblyopia (Ambly4Home)

The goal of this clinical trial is to evaluate a home-based augmented reality-based binocular therapy designed to improve visual function in adults aged 18 to 40 years with unilateral anisometropic amblyopia, commonly called "lazy eye." The therapy is designed to be used during everyday activities, allowing visual training to be integrated into the participant's normal home routine.

The main questions this study aims to answer are:

• Does the Ambly4Home augmented reality-based binocular therapy improve visual acuity in the amblyopic eye and binocular vision compared with placebo visual training?
• Are any improvements in visual function maintained 6 months after the treatment has ended?
• Is the treatment associated with changes in other measures of visual function, retinal structure and function, and visual brain function?

Participants will be randomly assigned to receive either active binocular therapy or placebo visual training. Both groups will use the same mixed-reality device, follow the same training schedule, and carry out similar daily activities while viewing their real-world surroundings through the device. In the active treatment, the image presented to the amblyopic eye will remain close to the natural scene, while the contrast of the image presented to the stronger eye will be selectively lowered. This gives the amblyopic eye a relative visual advantage, helping to rebalance the input from the two eyes and encouraging them to work together.

In the placebo group, participants will use the same device under the same conditions, but without the selective contrast reduction used in the active treatment. This comparison will allow researchers to isolate the specific effect of selectively lowering the contrast seen by the stronger eye.

Participants will:

• Complete 40-minute training sessions four times per week for 10 weeks.
• Learn how to use the system in a clinical setting before continuing the training at home.
• Attend assessment visits before treatment, after 10 weeks of treatment, and 6 months after treatment has ended.
• Complete tests of visual acuity, depth perception, suppression between the eyes, and contrast sensitivity, as well as retinal imaging, retinal function testing, and brain imaging.

Study Overview

• Status: Recruiting
• Conditions: Amblyopia; Anisometropic Amblyopia
• Intervention / Treatment: Device: Active Augmented Reality-Based Binocular Therapy; Device: Placebo Augmented Reality-Based Visual Training

Detailed Description

Amblyopia is a neurodevelopmental disorder characterized not only by reduced visual acuity in the amblyopic eye but also by abnormal interaction between the two eyes, including interocular suppression and impaired binocular integration. Although treatment has traditionally focused on childhood, evidence of residual visual plasticity in adults has supported the development of binocular and dichoptic approaches aimed at restoring a more balanced contribution from both eyes.

Dichoptic therapy simultaneously stimulates both eyes while presenting different visual inputs to each eye. A common strategy is to reduce the strength of the image presented to the stronger eye, allowing the amblyopic eye to contribute more effectively during binocular viewing. This approach differs from conventional occlusion because visual information from both eyes remains available throughout treatment.

The intervention evaluated in this study is designed to adapt this therapeutic principle to the daily life of adults with amblyopia. In contrast to fully immersive virtual reality approaches that require participants to interrupt their usual activities and engage in dedicated virtual tasks or games, the intervention uses a Meta Quest 3 mixed-reality headset operating in passthrough mode. Participants can therefore continue to view and interact with their real-world environment while controlled visual processing is applied separately to each eye. The intervention is intended to integrate binocular visual rehabilitation into functional activities performed in the home environment.

During active treatment, the real-world scene presented to the amblyopic eye is preserved as close as possible to natural viewing conditions. The dominant eye receives the same spatially corresponding scene, but with a controlled reduction in contrast. This contrast manipulation reduces the functional advantage of the dominant eye without completely removing its visual information, creating a relative visual advantage for the amblyopic eye and encouraging its more active participation during binocular viewing. The intervention therefore aims to progressively rebalance the contribution of the two eyes rather than replace binocular vision with monocular viewing.

The degree of contrast modulation will be individualized according to the participant's visual function and adjusted throughout treatment according to visual performance. As visual function improves, the contrast difference between the eyes can be progressively reduced, bringing the visual inputs closer to natural binocular viewing conditions. This adaptive approach is intended to maintain an appropriate therapeutic challenge while avoiding unnecessary or excessive penalization of the dominant eye.

The study uses a randomized, placebo-controlled design in which both groups use the same mixed-reality device and follow the same training routine. The placebo condition preserves the device experience, duration, tasks, instructions, and home-use context but does not include the selective interocular contrast manipulation that produces active binocular rebalancing. This design allows the specific effect of the dichoptic treatment mechanism to be distinguished from nonspecific effects related to repeated visual activity, familiarity with the device, attention, and treatment expectations.

The home-based intervention is also designed to support objective monitoring of treatment exposure. Information such as session completion, effective training duration, interruptions, visual settings, task performance, adherence, and tolerability may be recorded to characterize the actual treatment dose and support individualized progression. Functional activities will be selected according to the participant's visual ability and safety, allowing the difficulty of the training to increase gradually as adaptation and visual performance improve.

In addition to determining the clinical effect of the binocular intervention, the study uses a multimodal assessment approach to characterize visual, retinal, and cortical changes associated with treatment and to investigate whether any improvements persist after treatment has ended. This approach is intended to provide a broader understanding of the functional and neurobiological response to home-based augmented reality binocular rehabilitation in adults with anisometropic amblyopia.

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Catarina A Mateus, PhD; Phone Number: +351 962662157; Email: cms@ess.ipp.pt
• Study Contact Backup: Name: Rúben Magalhães, MSc; Phone Number: +351 968918180; Email: rjcm@ess.ipp.pt

Study Locations

• Portugal
  • Coimbra District
    • Coimbra, Coimbra District, Portugal, 3000-548
      • Recruiting
      • Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra
      • Principal Investigator: Miguel Castelo-Branco, MD, PhD
      • Sub-Investigator: João Castelhano, PhD
      • Sub-Investigator: Sónia Pires, BSc
      • Sub-Investigator: Sónia Afonso, MSc
      • Contact: Miguel Castelo-Branco, MD, PhD; Phone Number: +351 239488510; Email: mcbranco@fmed.uc.pt
      • Sub-Investigator: Otília Cardoso de Almeida, PhD
  • Porto District
    • Porto, Porto District, Portugal, 4200-072
      • Recruiting
      • RISE-Health, Center for Translational Health and Medical Biotechnology Research (TBIO), School of Health, Polytechnic of Porto
      • Principal Investigator: Catarina Mateus, PhD
      • Contact: Nuno B Rocha, PhD; Phone Number: +351 934540007; Email: nrocha@ess.ipp.pt
      • Sub-Investigator: Nuno Rocha, PhD
      • Sub-Investigator: Rúben Magalhães, MSc
      • Sub-Investigator: Simão Ferreira, PhD
      • Sub-Investigator: Inês Pais, MSc
      • Sub-Investigator: Natália Almeida-Antunes, PhD
      • Sub-Investigator: Filipe Coelho, MSc
      • Sub-Investigator: Libânia Dias, BSc
      • Sub-Investigator: Cleuber Alves, BSc

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age between 18 and 40 years.
• Diagnosis of anisometropic amblyopia, defined as unilateral amblyopia with an interocular difference of at least 2 lines in best-corrected visual acuity (BCVA), with BCVA worse than 20/32 in the more affected eye.

Exclusion Criteria:

• Amblyopia other than anisometropic amblyopia.
• Bilateral amblyopia.
• Ophthalmologic or neuro-ophthalmologic disease other than amblyopia.
• Neurological disease, chronic pharmacological therapy, or implanted medical devices.
• Any ocular surgery or ocular treatment within the previous year.
• Significant media opacities that may prevent fundus examination.
• Inability to provide informed consent.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Active Augmented Reality-Based Binocular Therapy; Participants will receive active augmented reality-based binocular therapy for 10 weeks, with 40-minute sessions four times per week, initially in a clinical setting and subsequently at home.	Device: Active Augmented Reality-Based Binocular Therapy; Active augmented reality-based binocular therapy will be delivered using a Meta Quest 3 mixed-reality headset operating in passthrough mode. Participants will complete 40-minute sessions four times per week for 10 weeks, initially learning to use the system in a clinical setting and subsequently continuing the training at home. The real-world scene presented to the amblyopic eye will remain close to natural viewing, while the contrast presented to the dominant eye will be selectively reduced. This controlled contrast reduction gives the amblyopic eye a relative visual advantage, encouraging its more active contribution during binocular viewing and promoting binocular integration. The degree of contrast modulation will be adjusted according to visual performance over the course of treatment.
Placebo Comparator: Placebo Augmented Reality-Based Visual Training; Participants will receive placebo augmented reality-based visual training for 10 weeks, with 40-minute sessions four times per week, using the same mixed-reality device and training schedule as the active group.	Device: Placebo Augmented Reality-Based Visual Training; Placebo augmented reality-based visual training will be delivered using the same Meta Quest 3 mixed-reality headset operating in passthrough mode, with the same session duration, training schedule, and home-based setting as the active intervention. Participants will view and interact with their real-world surroundings while carrying out similar visual activities. Unlike the active intervention, the contrast presented to the dominant eye will not be selectively reduced. The visual information presented to both eyes will remain equivalent or will be only minimally and symmetrically modified, without providing active binocular rebalancing or a therapeutic visual advantage to the amblyopic eye.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change From Baseline in Best-Corrected Visual Acuity of the Amblyopic Eye at Week 10	Best-corrected visual acuity of the amblyopic eye will be assessed monocularly using a standardized ETDRS chart and recorded as the number of letters correctly identified. Higher ETDRS letter scores indicate better visual acuity. Change from baseline will be calculated as the Week 10 letter score minus the baseline letter score. A positive change indicates an improvement in visual acuity.	Baseline and Week 10

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change From Baseline in Near Stereoacuity at Week 10	Near stereoacuity will be assessed binocularly using a graded circles stereotest with polarized glasses and recorded in seconds of arc. Measurable stereoacuity ranges from 400 to 20 seconds of arc. Lower values indicate better stereoacuity. Change from baseline will be calculated as the Week 10 value minus the baseline value. A negative change indicates an improvement. Participants unable to identify the largest disparity will be classified as having no measurable stereoacuity.	Baseline and Week 10
Change From Baseline in Interocular Suppression at Week 10	Interocular suppression will be assessed under binocular viewing conditions using a standardized suppression test. The outcome will be the filter level at which binocular perception changes. Change from baseline will be calculated as the Week 10 value minus the baseline value.	Baseline and Week 10
Change From Baseline in Cortical Population Receptive Field Size at Week 10	Cortical population receptive field (pRF) size will be assessed using functional magnetic resonance imaging (fMRI)-based retinotopic mapping. Mean pRF size will be estimated separately for the early visual areas V1, V2, and V3.	Baseline and Week 10
Change From Baseline in Best-Corrected Visual Acuity of the Amblyopic Eye at 6-Month Follow-up	Best-corrected visual acuity of the amblyopic eye will be assessed monocularly using a standardized ETDRS chart and recorded as the number of letters correctly identified. Higher ETDRS letter scores indicate better visual acuity. Change from baseline will be calculated as the 6-month follow-up letter score minus the baseline letter score. A positive change indicates an improvement in visual acuity.	Baseline and 6 months after treatment completion
Change From Baseline in Near Stereoacuity at 6-Month Follow-up	Near stereoacuity will be assessed binocularly using a graded circles stereotest with polarized glasses and recorded in seconds of arc. Measurable stereoacuity ranges from 400 to 20 seconds of arc. Lower values indicate better stereoacuity. Change from baseline will be calculated as the 6-month follow-up value minus the baseline value. A negative change indicates an improvement. Participants unable to identify the largest disparity will be classified as having no measurable stereoacuity.	Baseline and 6 months after treatment completion
Change From Baseline in Interocular Suppression at 6-Month Follow-up	Interocular suppression will be assessed under binocular viewing conditions using a standardized suppression test. The outcome will be the filter level at which binocular perception changes. Change from baseline will be calculated as the 6-month follow-up value minus the baseline value.	Baseline and 6 months after treatment completion
Change From Baseline in Static Achromatic Contrast Sensitivity in the Amblyopic Eye at Week 10	Static achromatic contrast sensitivity will be assessed monocularly in the amblyopic and fellow eyes using the MonCV3 system (Metrovision). Sinusoidal gratings will be presented at a temporal frequency of 0 Hz and at spatial frequencies of 0.55, 1.1, 2.2, 3.4, 7.1, and 14.2 cycles per degree. Results will be recorded in decibels (dB) separately for each eye and spatial frequency, with higher values indicating better contrast sensitivity. Change from baseline will be calculated as the Week 10 value minus the baseline value. A positive change indicates improvement.	Baseline and Week 10
Change From Baseline in Static Achromatic Contrast Sensitivity in the Amblyopic Eye at 6-Month Follow-up	Static achromatic contrast sensitivity will be assessed monocularly in the amblyopic and fellow eyes using the MonCV3 system (Metrovision). Sinusoidal gratings will be presented at a temporal frequency of 0 Hz and at spatial frequencies of 0.55, 1.1, 2.2, 3.4, 7.1, and 14.2 cycles per degree. Results will be recorded in decibels (dB) separately for each eye and spatial frequency, with higher values indicating better contrast sensitivity. Change from baseline will be calculated as the 6-month follow-up value minus the baseline value. A positive change indicates improvement.	Baseline and 6 months after treatment completion
Change From Baseline in Retinal Neuronal Layer Thicknesses at Week 10	Retinal structure will be assessed in the amblyopic and fellow eyes using the CIRRUS HD-OCT 5000 (ZEISS). The outcome measures will include total macular thickness, macular ganglion cell-inner plexiform layer (GCIPL) thickness, and peripapillary retinal nerve fiber layer (RNFL) thickness. Measurements will be recorded in micrometers (µm) and analyzed separately for each eye and prespecified retinal sector. Change from baseline will be calculated as the Week 10 value minus the baseline value for each thickness parameter.	Baseline and Week 10
Change From Baseline in Retinal Neuronal Layer Thicknesses at 6-Month Follow-up	Retinal structure will be assessed in the amblyopic and fellow eyes using the CIRRUS HD-OCT 5000 (ZEISS). The outcome measures will include total macular thickness, macular ganglion cell-inner plexiform layer (GCIPL) thickness, and peripapillary retinal nerve fiber layer (RNFL) thickness. Measurements will be recorded in micrometers (µm) and analyzed separately for each eye and prespecified retinal sector. Change from baseline will be calculated as the 6-month follow-up value minus the baseline value for each thickness parameter.	Baseline and 6 months after treatment completion
Change From Baseline in Retinal Ganglion Cell Function Assessed by Pattern Electroretinography at Week 10	Retinal ganglion cell function will be assessed in the amblyopic and fellow eyes using pattern electroretinography (PERG) recorded with the Tomey EP-1000 Pro system. N95 amplitude, measured in microvolts (µV), and N95 implicit time, measured in milliseconds (ms), will be extracted and analyzed separately for each eye. Change from baseline will be calculated as the Week 10 value minus the baseline value for each PERG parameter.	Baseline and Week 10
Change From Baseline in Retinal Ganglion Cell Function Assessed by Pattern Electroretinography at 6-Month Follow-up	Retinal ganglion cell function will be assessed in the amblyopic and fellow eyes using pattern electroretinography (PERG) recorded with the Tomey EP-1000 Pro system. N95 amplitude, measured in microvolts (µV), and N95 implicit time, measured in milliseconds (ms), will be extracted and analyzed separately for each eye. Change from baseline will be calculated as the 6-month follow-up value minus the baseline value for each PERG parameter.	Baseline and 6 months after treatment completion
Change From Baseline in Cortical Population Receptive Field Size at 6-Month Follow-up	Cortical population receptive field (pRF) size will be assessed using functional magnetic resonance imaging (fMRI)-based retinotopic mapping. Mean pRF size will be estimated separately for the early visual areas V1, V2, and V3.	Baseline and 6 months after treatment completion

Collaborators and Investigators

• Sponsor: Polytechnic Institute of Porto
• Collaborators: University of Coimbra; OPTIMIZER - Serviços e Consultadoria Informática, Lda.; LINOVT - Engenharia Software, Lda.

Publications and helpful links

General Publications

• Ziak P, Holm A, Halicka J, Mojzis P, Pinero DP. Amblyopia treatment of adults with dichoptic training using the virtual reality oculus rift head mounted display: preliminary results. BMC Ophthalmol. 2017 Jun 28;17(1):105. doi: 10.1186/s12886-017-0501-8.
• Levi DM. Rethinking amblyopia 2020. Vision Res. 2020 Nov;176:118-129. doi: 10.1016/j.visres.2020.07.014. Epub 2020 Aug 28.
• Pineles SL, Aakalu VK, Hutchinson AK, Galvin JA, Heidary G, Binenbaum G, VanderVeen DK, Lambert SR. Binocular Treatment of Amblyopia: A Report by the American Academy of Ophthalmology. Ophthalmology. 2020 Feb;127(2):261-272. doi: 10.1016/j.ophtha.2019.08.024. Epub 2019 Oct 13.
• Bui Quoc E, Kulp MT, Burns JG, Thompson B. Amblyopia: A review of unmet needs, current treatment options, and emerging therapies. Surv Ophthalmol. 2023 May-Jun;68(3):507-525. doi: 10.1016/j.survophthal.2023.01.001. Epub 2023 Jan 18.
• Wang M, Ding J, Levi DM, Cooper EA. The Effect of Interocular Contrast Differences on the Appearance of Augmented Reality Imagery. ACM Transactions on Applied Perception. 2024;21(1):1-23. doi:10.1145/3617684.
• Thompson B, Concetta Morrone M, Bex P, Lozama A, Sabel BA. Harnessing brain plasticity to improve binocular vision in amblyopia: An evidence-based update. Eur J Ophthalmol. 2024 Jul;34(4):901-912. doi: 10.1177/11206721231187426. Epub 2023 Jul 10.
• Tan F, Yang X, Fan Y, Liao Y. The Study of Short-Term Plastic Visual Perceptual Training Based on Virtual and Augmented Reality Technology in Amblyopia. J Ophthalmol. 2022 Sep 1;2022:2826724. doi: 10.1155/2022/2826724. eCollection 2022.
• Hess RF, Thompson B. Amblyopia and the binocular approach to its therapy. Vision Res. 2015 Sep;114:4-16. doi: 10.1016/j.visres.2015.02.009. Epub 2015 Apr 20.

Study record dates

Study Major Dates

• Study Start (Actual): May 1, 2026
• Primary Completion (Estimated): January 31, 2028
• Study Completion (Estimated): January 31, 2028

Study Registration Dates

• First Submitted: September 8, 2026
• First Submitted That Met QC Criteria: September 8, 2026
• First Posted (Actual): September 15, 2026

Study Record Updates

• Last Update Posted (Actual): September 15, 2026
• Last Update Submitted That Met QC Criteria: September 8, 2026
• Last Verified: September 1, 2026

More Information

Terms related to this study

• Keywords: Augmented Reality; Adult Amblyopia; Anisometropic Amblyopia; Dichoptic Therapy; Binocular Therapy; Interocular Suppression; Interocular Contrast Modulation; Home-Based Visual Rehabilitation
• Additional Relevant MeSH Terms: Neurologic Manifestations; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Eye Diseases; Vision Disorders; Sensation Disorders; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Amblyopia
• Other Study ID Numbers: ORT-2026-003; COMPETE2030-FEDER-01469700 (Other Grant/Funding Number: Portugal 2030 - COMPETE 2030)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared because the approved data protection plan limits the use of coded study data to this project and does not permit their transfer to other institutions, investigators, or countries. Study findings may be disseminated only in aggregated, non-identifiable form.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No