Trial of Vision Therapy for Intermittent Exotropia

Study Overview
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Brief Summary
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The main objective of this randomized trial comparing vision therapy to observation is to determine the short-term effectiveness of vision therapy on distance intermittent exotropia control. The results will help determine whether to proceed to a full-scale, long-term randomized trial.

Detailed Description
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Vision therapy (VT) is a commonly prescribed treatment for children with intermittent exotropia (IXT). The effectiveness of VT as a treatment modality for children with IXT is unknown because previous studies have largely limited observational or retrospective case series without comparison groups. The objective of this multi-centered pilot randomized trial of VT for IXT compared to observation is to 1) determine the short-term effectiveness of VT on distance intermittent exotropia and 2) determine the feasibility of recruitment and retention of children aged 8 to 16 years old with IXT to participate in a randomized trial of 20 weeks of in-office VT. The results of this trial will provide the needed information to plan and conduct a large-scale randomized trial to determine short-term and long-term effectiveness of VT for IXT in children, with the full-scale randomized trial helping to fill in the gaps in scientific knowledge concerning VT as a treatment for IXT.

Official Title
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A Pilot Randomized Trial Evaluating Short-Term Effectiveness of Vision Therapy in Children With Intermittent Exotropia

Conditions
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Intermittent Exotropia

Intervention / Treatment
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* Other: Vision Therapy


Participation Criteria
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Eligibility Criteria
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Major Inclusion Criteria- Age 8 - 16 years Intermittent exotropia meeting all of the following: Distance exodeviation of 15∆ to 35∆ by prism alternating cover test (PACT) IXT, exophoria, or orthophoria at near Near exodeviation that does not exceed the distance exodeviation by more than 10∆ Mean distance control score of 2 points or more with at least one measure being 3 points or higher Mean near control score less than 5 points Random dot stereopsis of 200 or better on Preschool Randot Stereotest Willingness to accept randomization and no plan to relocate in the next 6 months Major Exclusion Criteria- Treatment for IXT or amblyopia (other than refractive correction) within 3 months prior to enrollment Office-based vision therapy for IXT within 6 months prior to enrollment Prior office-based vision therapy for IXT of ≥10 sessions Prior strabismus, intraocular, or refractive surgery (including BOTOX injection)

Ages Eligible for Study
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Minimum Age: 8 Years
Maximum Age: 16 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Vision Therapy<br>Participants will receive 20 consecutive weeks of office-based vision therapy with home therapy. | Other: Vision Therapy<br>* 20 consecutive weeks of office-based vision therapy with home therapy that aim to improve the participant's vergence skills, accommodative skills, and sensory fusion.<br>* Other names: Orthoptics;|
| No Intervention: Observation<br>Participants will receive no treatment for IXT is received during the study unless one of the deterioration criteria is met. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mean Distance Control Score | The primary analysis will be an intent-to-treat comparison of mean distance control score, determine by the intermittent exotropia office control scale, at outcome using an analysis of covariance model, which will adjust for baseline distance control. The intermittent exotropia office control scale grades the control on a scale of 0 (best control; phoria) to 5 (worst control; constant exotropia). | 21 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| No Spontaneous Tropia | The proportion of participants with no spontaneous tropia at outcome will be compared between treatment groups.No spontaneous tropia is defined as control score of 2 or less on all three assessments of control at distance and near and no exotropia lasting more than 5 seconds throughout the examination. | 21 weeks | 
| Change in Distance Control | The proportion of participants with >= 1 point change in control and >= 2 points change in control will be compared between treatment groups. | 21 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Intermittent Exotropia, Vision Therapy