Intermittent StrabismusViT(I)SNCT07563959
Visual Therapy for Intermittent Strabismus
A study testing Visual Therapy in people with Intermittent Strabismus and Exotropia Intermittent, run by Universitat Politècnica de Catalunya.
Trial summary
Intermittent strabismus is a condition in which the eyes occasionally become misaligned, affecting binocular vision, depth perception, and quality of life. Standard treatment often involves surgery of the eye muscles, although its effectiveness and timing remain debated. Read more about this study
- Who is it for?
- Ages 8 to 50 years
- Conditions the study is for
- Intermittent Strabismus, Exotropia Intermittent, Esotropia Intermittent
- What is being tested?
- Visual Therapy
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 30 participants
- Where
- No sites listed yet
- Study dates
- 1 May 2026to 1 Jul 2028
- 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 8 to 50 years
- All sexes
- No healthy volunteers
- Child, Adult
Who may be able to join
- Individuals aged 8 to 50 years Diagnosis of intermittent horizontal strabismus (exotropia or esotropia) Absence of associated ocular, systemic, or neurological pathology Ability to understand and follow study instructions Willingness and motivation to complete 12 sessions of visual therapy (for the experimental group) Written informed consent (and assent for minors when applicable)
Who cannot join
- Previous visual therapy treatment Inability to attend in-office visual therapy sessions Presence of ocular, systemic, or neurological disease affecting vision Constant strabismus Cognitive or intellectual impairment limiting the ability to perform the exercises
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
About this study
Official title: Efficacy of Visual Therapy in Intermittent Non-Pathological Horizontal Strabismus: A Randomized Controlled Trial
Intermittent strabismus is a condition in which the eyes occasionally become misaligned, affecting binocular vision, depth perception, and quality of life. Standard treatment often involves surgery of the eye muscles, although its effectiveness and timing remain debated.
Visual therapy is a non-invasive alternative that uses structured exercises to improve eye coordination and binocular vision. However, there is limited high-quality evidence supporting its effectiveness in intermittent strabismus.
Read more
This randomized controlled trial aims to evaluate whether a 12-session visual therapy program improves eye alignment, binocular vision, control of strabismus, and quality of life in individuals aged 8 to 50 years with intermittent horizontal strabismus.
Participants will be assigned to either a visual therapy group or a control group without treatment. Visual therapy will include weekly in-office sessions combined with short daily home exercises.
The study will assess changes before and after the intervention to determine whether visual therapy is an effective, non-invasive treatment option that could reduce the need for surgery.
Read the detailed description
Strabismus is a heterogeneous condition that may arise from alterations in extraocular muscles, their innervation, or central nervous system mechanisms. In this study, strabismus refers specifically to intermittent horizontal strabismus not associated with ocular, systemic, or neurological pathology, nor with orbital or craniofacial abnormalities.
Surgical correction of extraocular muscles is currently the main treatment approach. However, controversy exists regarding surgical indications, timing, and long-term outcomes. Furthermore, growing evidence suggests that many cases of strabismus may be related to central nervous system dysfunction rather than primary muscular abnormalities.
Visual therapy (VT) is a non-invasive intervention consisting of structured exercises designed to improve oculomotor control and enhance sensory and motor fusion. Neuroimaging studies have demonstrated central nervous system changes following VT in conditions such as convergence insufficiency, supporting its potential mechanism of action.
Despite these findings, evidence supporting VT for intermittent strabismus remains limited and is primarily based on case series and retrospective studies. Therefore, a prospective, randomized controlled trial is needed.
This study is a single-center, prospective, randomized, controlled, single-masked clinical trial conducted at Hospital Universitari Mútua de Terrassa.
Participants aged 8 to 50 years with intermittent horizontal strabismus will be recruited and randomly assigned to:
Experimental group: visual therapy Control group: no treatment during the study period
The intervention will consist of 12 weekly in-office sessions (1 hour each) at the Centre Universitari de la Visió, combined with daily home-based exercises (~10 minutes), with adherence monitoring.
Outcome assessments will be conducted at baseline (T0) and post-treatment (T1) using standardized optometric procedures. Outcome assessors will be masked to group allocation to minimize bias.
Primary outcomes include changes in ocular deviation measured using alternate cover test with prism bars and Hirschberg test. Secondary outcomes include binocular function (fusion and stereopsis), control of deviation (Mohney and Holmes Office Control Score), and vision-related quality of life (AS-20 for adults and IXTQ for children).
Statistical analysis will compare pre- and post-intervention changes between groups using repeated measures models or equivalent non-parametric tests where appropriate.
The intervention poses minimal risk, as it is non-invasive and does not involve pharmacological treatment. Potential risks are limited to mild visual fatigue or unmet expectations, which will be mitigated through appropriate participant information.
This study aims to determine whether visual therapy can serve as an effective, non-invasive treatment for intermittent strabismus and potentially reduce the need for surgical intervention.
- Being tested
- Visual Therapy
- Keywords
- Intermittent Strabismus, Visual Therapy, Binocular Vision, Exotropia, Esotropia, Pediatric and Adult Strabismus, Quality of Life
- Medical subject headings
- Esotropia, Exotropia, Strabismus
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Visual TherapyBehavioural
A structured program of visual exercises designed to improve oculomotor control and binocular vision. The intervention includes 12 weekly in-office sessions (1 hour each) conducted at a specialized center, combined with daily home-based exercises (~10 minutes), with adherence monitoring.
| Study group | Role | What they receive |
|---|---|---|
| Visual Therapy | Experimental | Participants will receive a structured visual therapy program consisting of 12 weekly in-office sessions (1 hour each) combined with daily home-based exercises (~10 minutes), with adherence monitoring. Receives: Behavioral: Visual Therapy |
| Control | No intervention | Participants will not receive any intervention during the study period. They will undergo the same baseline and post-study assessments as the experimental group. |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Ocular Deviation
Ocular deviation will be assessed using the alternate cover test with prism bars in primary gaze and Hirschberg test with image capture. The magnitude of deviation will be expressed in prism diopters (PD).
Measured: Baseline (T0) to 12 weeks (T1)
Change in Binocular Function (Fusion and Stereopsis)
Binocular function will be assessed using the Worth 4 Dot test (fusion) and stereopsis tests at near distance.
Measured: Baseline (T0) to 12 weeks (T1)
Change in Strabismus Control
Control of strabismus will be assessed using the Mohney and Holmes Office Control Score, a 5-point ordinal scale evaluating the frequency and control of ocular deviation.
Measured: Baseline (T0) to 12 weeks (T1)
Change in Vision-Related Quality of Life
Quality of life will be assessed using validated questionnaires: AS-20 for adults and Intermittent Exotropia Questionnaire (IXTQ) for pediatric participants.
Measured: Baseline (T0) to 12 weeks (T1)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted4 May 2026
- Study start1 May 2026 (estimated)
- Primary completion1 Jul 2028 (estimated)
- Study completion1 Jul 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (6)Papers the sponsor has linked to this study.
- Other trials for Intermittent StrabismusStudies 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
- Model description
- Participants will be randomized into two parallel groups. The experimental group will receive a structured visual therapy program consisting of 12 weekly in-office sessions combined with daily home-based exercises. The control group will not receive any intervention during the study period. Outcomes will be assessed at baseline and after completion of the intervention to compare changes between groups.
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 30 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Universitat Politècnica de Catalunya
- Sponsor type
- University, hospital or other
- Collaborators
- Hospital Universitari Mútua de Terrassa
- Responsible party
- Principal investigator, Laura Asensio Jurado, Universitat Politècnica de Catalunya
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07563959
- Sponsor's protocol ID
- ViT(I)S
- Acronym
- ViT(I)S
- Status last verified
- Apr 2026
- First submitted
- 26 Apr 2026
- Last updated
- 4 May 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Publications
Sunyer-Grau B, Quevedo L, Rodriguez-Vallejo M, Argiles M. Comitant strabismus etiology: extraocular muscle integrity and central nervous system involvement-a narrative review. Graefes Arch Clin Exp Ophthalmol. 2023 Jul;261(7):1781-1792. doi: 10.1007/s00417-022-05935-9. Epub 2023 Jan 21.
PubMed 36680614Sunyer-Grau B, Quevedo L, Rodriguez-Vallejo M, Argiles M. Surgical outcomes and etiological considerations in intermittent exotropia: a systematic narrative review. Strabismus. 2025 Sep;33(3):188-198. doi: 10.1080/09273972.2024.2449563. Epub 2025 Jan 7.
PubMed 39773345Ma MM, Kang Y, Chen C, Su C, Tian Z, Le M. Vision therapy for intermittent exotropia: A case series. J Optom. 2021 Jul-Sep;14(3):247-253. doi: 10.1016/j.optom.2020.05.006. Epub 2020 Aug 12.
PubMed 32800454Pang Y, Gnanaraj L, Gayleard J, Han G, Hatt SR. Interventions for intermittent exotropia. Cochrane Database Syst Rev. 2021 Sep 13;9(9):CD003737. doi: 10.1002/14651858.CD003737.pub4.
PubMed 34516656Alvarez TL, Vicci VR, Alkan Y, Kim EH, Gohel S, Barrett AM, Chiaravalloti N, Biswal BB. Vision therapy in adults with convergence insufficiency: clinical and functional magnetic resonance imaging measures. Optom Vis Sci. 2010 Dec;87(12):E985-1002. doi: 10.1097/OPX.0b013e3181fef1aa.
PubMed 21057347Bui Quoc E, Milleret C. Origins of strabismus and loss of binocular vision. Front Integr Neurosci. 2014 Sep 25;8:71. doi: 10.3389/fnint.2014.00071. eCollection 2014.
PubMed 25309358
Study at a glance
From the registry record, last updated by the sponsor on 4 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Efficacy of Visual Therapy in Intermittent Non-Pathological Horizontal Strabismus: A Randomized Controlled Trial
- ClinicalTrials.gov ID
- NCT07563959
- Acronym / sponsor ID
- ViT(I)S / ViT(I)S
- Keywords
- Intermittent Strabismus, Visual Therapy, Binocular Vision, Exotropia, Esotropia, Pediatric and Adult Strabismus, Quality of Life
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 30 participants (estimated)
- Lead sponsor
- Universitat Politècnica de CatalunyaUniversity, hospital or other
- Collaborators
- Hospital Universitari Mútua de Terrassa
- Study start
- 1 May 2026 (estimated)
- Primary completion
- 1 Jul 2028 (estimated)
- Study completion
- 1 Jul 2028 (estimated)
- First posted
- 4 May 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.
Intermittent strabismus is a condition in which the eyes occasionally become misaligned, affecting binocular vision, depth perception, and quality of life. Standard treatment often involves surgery of the eye muscles, although its effectiveness and timing remain debated.
Visual therapy is a non-invasive alternative that uses structured exercises to improve eye coordination and binocular vision. However, there is limited high-quality evidence supporting its effectiveness in intermittent strabismus.
This randomized controlled trial aims to evaluate whether a 12-session visual therapy program improves eye alignment, binocular vision, control of strabismus, and quality of life in individuals aged 8 to 50 years with intermittent horizontal strabismus.
Participants will be assigned to either a visual therapy group or a control group without treatment. Visual therapy will include weekly in-office sessions combined with short daily home exercises.
The study will assess changes before and after the intervention to determine whether visual therapy is an effective, non-invasive treatment option that could reduce the need for surgery.
Detailed description
Strabismus is a heterogeneous condition that may arise from alterations in extraocular muscles, their innervation, or central nervous system mechanisms. In this study, strabismus refers specifically to intermittent horizontal strabismus not associated with ocular, systemic, or neurological pathology, nor with orbital or craniofacial abnormalities.
Surgical correction of extraocular muscles is currently the main treatment approach. However, controversy exists regarding surgical indications, timing, and long-term outcomes. Furthermore, growing evidence suggests that many cases of strabismus may be related to central nervous system dysfunction rather than primary muscular abnormalities.
Visual therapy (VT) is a non-invasive intervention consisting of structured exercises designed to improve oculomotor control and enhance sensory and motor fusion. Neuroimaging studies have demonstrated central nervous system changes following VT in conditions such as convergence insufficiency, supporting its potential mechanism of action.
Despite these findings, evidence supporting VT for intermittent strabismus remains limited and is primarily based on case series and retrospective studies. Therefore, a prospective, randomized controlled trial is needed.
This study is a single-center, prospective, randomized, controlled, single-masked clinical trial conducted at Hospital Universitari Mútua de Terrassa.
Participants aged 8 to 50 years with intermittent horizontal strabismus will be recruited and randomly assigned to:
Experimental group: visual therapy Control group: no treatment during the study period
The intervention will consist of 12 weekly in-office sessions (1 hour each) at the Centre Universitari de la Visió, combined with daily home-based exercises (~10 minutes), with adherence monitoring.
Outcome assessments will be conducted at baseline (T0) and post-treatment (T1) using standardized optometric procedures. Outcome assessors will be masked to group allocation to minimize bias.
Primary outcomes include changes in ocular deviation measured using alternate cover test with prism bars and Hirschberg test. Secondary outcomes include binocular function (fusion and stereopsis), control of deviation (Mohney and Holmes Office Control Score), and vision-related quality of life (AS-20 for adults and IXTQ for children).
Statistical analysis will compare pre- and post-intervention changes between groups using repeated measures models or equivalent non-parametric tests where appropriate.
The intervention poses minimal risk, as it is non-invasive and does not involve pharmacological treatment. Potential risks are limited to mild visual fatigue or unmet expectations, which will be mitigated through appropriate participant information.
This study aims to determine whether visual therapy can serve as an effective, non-invasive treatment for intermittent strabismus and potentially reduce the need for surgical intervention.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 2
- Model description
- Participants will be randomized into two parallel groups. The experimental group will receive a structured visual therapy program consisting of 12 weekly in-office sessions combined with daily home-based exercises. The control group will not receive any intervention during the study period. Outcomes will be assessed at baseline and after completion of the intervention to compare changes between groups.
| Arm | Type | Receives |
|---|---|---|
| Visual Therapy | Experimental | Behavioral: Visual TherapyParticipants will receive a structured visual therapy program consisting of 12 weekly in-office sessions (1 hour each) combined with daily home-based exercises (~10 minutes), with adherence monitoring. |
| Control | No intervention | –Participants will not receive any intervention during the study period. They will undergo the same baseline and post-study assessments as the experimental group. |
Who may qualify
- Ages
- 8 to 50 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult
Key inclusion criteria (1 listed)
- Individuals aged 8 to 50 years Diagnosis of intermittent horizontal strabismus (exotropia or esotropia) Absence of associated ocular, systemic, or neurological pathology Ability to understand and follow study instructions Willingness and motivation to complete 12 sessions of visual therapy (for the experimental group) Written informed consent (and assent for minors when applicable)
Key exclusion criteria (1 listed)
- Previous visual therapy treatment Inability to attend in-office visual therapy sessions Presence of ocular, systemic, or neurological disease affecting vision Constant strabismus Cognitive or intellectual impairment limiting the ability to perform the exercises
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 |
|---|---|---|
| Visual TherapyA structured program of visual exercises designed to improve oculomotor control and binocular vision. The intervention includes 12 weekly in-office sessions (1 hour each) conducted at a specialized center, combined with daily home-based exercises (~10 minutes), with adherence monitoring. | Behavioural | Visual Therapy |
Primary outcome
Change in Ocular Deviation
Time frame: Baseline (T0) to 12 weeks (T1)
Ocular deviation will be assessed using the alternate cover test with prism bars in primary gaze and Hirschberg test with image capture. The magnitude of deviation will be expressed in prism diopters (PD).
Change in Binocular Function (Fusion and Stereopsis)
Time frame: Baseline (T0) to 12 weeks (T1)
Binocular function will be assessed using the Worth 4 Dot test (fusion) and stereopsis tests at near distance.
Change in Strabismus Control
Time frame: Baseline (T0) to 12 weeks (T1)
Control of strabismus will be assessed using the Mohney and Holmes Office Control Score, a 5-point ordinal scale evaluating the frequency and control of ocular deviation.
Change in Vision-Related Quality of Life
Time frame: Baseline (T0) to 12 weeks (T1)
Quality of life will be assessed using validated questionnaires: AS-20 for adults and Intermittent Exotropia Questionnaire (IXTQ) for pediatric participants.
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 4 May 2026.
- Results publication: PubMed 36680614Sunyer-Grau B, Quevedo L, Rodriguez-Vallejo M, Argiles M. Comitant strabismus etiology: extraocular muscle integrity and central nervous system involvement-a narrative review. Graefes Arch Clin Exp Ophthalmol. 2023 Jul;261(7):1781-1792. doi: 10.1007/s00417-022-05935-9. Epub 2023 Jan 21.
- Results publication: PubMed 39773345Sunyer-Grau B, Quevedo L, Rodriguez-Vallejo M, Argiles M. Surgical outcomes and etiological considerations in intermittent exotropia: a systematic narrative review. Strabismus. 2025 Sep;33(3):188-198. doi: 10.1080/09273972.2024.2449563. Epub 2025 Jan 7.
- Results publication: PubMed 32800454Ma MM, Kang Y, Chen C, Su C, Tian Z, Le M. Vision therapy for intermittent exotropia: A case series. J Optom. 2021 Jul-Sep;14(3):247-253. doi: 10.1016/j.optom.2020.05.006. Epub 2020 Aug 12.
- Results publication: PubMed 34516656Pang Y, Gnanaraj L, Gayleard J, Han G, Hatt SR. Interventions for intermittent exotropia. Cochrane Database Syst Rev. 2021 Sep 13;9(9):CD003737. doi: 10.1002/14651858.CD003737.pub4.
- Results publication: PubMed 21057347Alvarez TL, Vicci VR, Alkan Y, Kim EH, Gohel S, Barrett AM, Chiaravalloti N, Biswal BB. Vision therapy in adults with convergence insufficiency: clinical and functional magnetic resonance imaging measures. Optom Vis Sci. 2010 Dec;87(12):E985-1002. doi: 10.1097/OPX.0b013e3181fef1aa.
- Results publication: PubMed 25309358Bui Quoc E, Milleret C. Origins of strabismus and loss of binocular vision. Front Integr Neurosci. 2014 Sep 25;8:71. doi: 10.3389/fnint.2014.00071. eCollection 2014.
- Individual participant dataSharing planned: Undecided
Related trials for Intermittent Strabismus
Not yet recruiting
Exercise Training on a Mirror for Intermittent Exotropia Control Post Strabismus Surgery
Exercise Training, Intermittent Exotropia
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.
Questions about this trial
What is this clinical trial studying?
A study testing Visual Therapy in people with Intermittent Strabismus and Exotropia Intermittent, run by Universitat Politècnica de Catalunya.
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 1 inclusion and 1 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 4 May 2026. Status can change between updates, so confirm with the study contact before making plans.
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 Laura Asensio Jurado, PhD (0034636760450, asensiojlaura@upc.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Ocular Deviation (time frame: Baseline (T0) to 12 weeks (T1)). The study lists 4 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07563959, which also lists 6 linked publications.
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 4 May 2026.