Efficacy of Visual Therapy in Intermittent Non-Pathological Horizontal Strabismus: A Randomized Controlled Trial
Trial Snapshot
- Phase
- Not Applicable
- Status
- Not yet recruiting
- Sponsor
- Enrollment
- 30
- Primary Endpoint
- Change in Ocular Deviation
Study Overview
Brief 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.
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.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Parallel
- Primary Purpose
- Treatment
- Masking
- Single (Outcomes Assessor)
Masking Description
Outcome assessors (optometrists) will be masked to group allocation. Participants and care providers cannot be masked due to the nature of the intervention.
Eligibility Criteria
- Ages
- 8 Years to 50 Years (Child, Adult)
- Sex
- All
- Accepts Healthy Volunteers
- No
Inclusion Criteria
- •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)
Exclusion Criteria
- •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
Arms & Interventions
Visual Therapy
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.
Intervention: Visual Therapy (Behavioral)
Control
Participants will not receive any intervention during the study period. They will undergo the same baseline and post-study assessments as the experimental group.
Outcomes
Primary Outcomes
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.
Secondary Outcomes
No secondary outcomes reported
Investigators
Laura Asensio Jurado
PhD
Universitat Politècnica de Catalunya