Objective Assessment of Disparity Vergence After Treatment of Symptomatic CI in Children

Study Overview
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Brief Summary
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This study is designed to evaluate changes in objective measures of disparity vergence after office-based vergence/accommodative therapy (OBVAT) for convergence insufficiency (CI) in children 12-17 years old.

Detailed Description
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30 participants with normal binocular vision and 30 with CI will be recruited for this prospective study. All participants with CI will be treated with 12 weeks of office-based vergence/accommodative therapy. The primary outcome measure will be the average peak velocity for 4° symmetrical convergence steps. Other objective outcome measures of disparity vergence will be time to peak velocity, latency, and accuracy. Changes in clinical measures [near point of convergence (NPC), positive fusional vergence at near (PFV)] and symptoms will be evaluated.

Official Title
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Objective Assessment of Disparity Vergence After Treatment of Symptomatic Convergence Insufficiency (CI) in Children

Conditions
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Convergence Insufficiency

Intervention / Treatment
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* Procedure: office-based vergence/accommodative therapy


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: CI Symptom Survey score ≥ 16 Exophoria at near at least 4 greater than at far Receded near point of convergence (NPC) of 6 cm break Insufficient positive fusional vergence (PFV) at near (i.e., failing Sheard's criterion or PFV ≤15 base-out break) Best-corrected distance visual acuity of 20/25 or better in each eye Random dot stereopsis appreciation of 500 seconds of arc or better Wearing appropriate refractive correction (spectacles of contact lenses) for at least 2 weeks prior to final determination of eligibility for any of the following uncorrected refractive errors (based on cycloplegic refraction within prior 12 months) No use of BI prism or plus add at near for 2 weeks prior to study and for duration of study Exclusion Criteria: Constant strabismus at distance or near Esophoria of ≥ 2∆ at distance Vertical heterophoria ≥ 2∆ at distance or near ≥ 2 line interocular difference in best-corrected visual acuity Near point of accommodation >20 cm in either eye as measured by push-up method Manifest or latent nystagmus History of strabismus surgery or refractive surgery CI associated with head trauma or known disease of the brain Diseases known to affect accommodation, vergence, or ocular motility Inability to comprehend and/or perform any study-related test

Ages Eligible for Study
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Minimum Age: 9 Years
Maximum Age: 17 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Interventional Model Description: Eligible participants received 12 weeks of office vergence/accommodative therapy
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Vision therapy group<br>Twelve, 60-minute, weekly visits of office-based vergence/accommodation therapy will be administered by a trained therapist combined with procedures to practice at home (15 minutes, 5 times per week). This treatment sequence is a well-accepted approach for treatment of CI and has been successfully implemented in previous studies. Fifteen minutes of home-based therapy was prescribed to be performed 5 days per week, and compliance with home-based therapy was monitored at each visit by the therapist | Procedure: office-based vergence/accommodative therapy<br>* one -to-one treatment by a trained therapists. The subject is asked to perform 5-6 therapy procedures during a 60 minute therapy session. The subject is also asked to perform 15 minutes per day of home-based therapy.<br>* Other names: optometric vision therapy;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in average peak velocity for 4° symmetrical convergence steps after 12 weeks of therapy | The ISCAN RK-826PCI binocular tracking system (Burlington, MA) will be used used to objectively record horizontal vergence eye movements. Five parameters will be measured with this instrument and the primary outcome measures will be the change in average peak velocity for 4° symmetrical convergence steps | After 12 weeks of therapy | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in time to peak velocity for 4° symmetrical convergence steps after 12 weeks of therapy | The ISCAN RK-826PCI binocular tracking system (Burlington, MA) will be used used to objectively record horizontal vergence eye movements. Five parameters will be measured with this instrument and a secondary outcome measures will be the change in time to peak velocity for 4° symmetrical convergence steps | After 12 weeks of therapy | 
| Change in latency for 4° symmetrical convergence steps after 12 weeks of therapy | The ISCAN RK-826PCI binocular tracking system (Burlington, MA) will be used used to objectively record horizontal vergence eye movements. Five parameters will be measured with this instrument and a secondary outcome measures will be the change in latency for 4° symmetrical convergence steps | After 12 weeks of therapy | 
| Change in accuracy for 4° symmetrical convergence steps after 12 weeks of therapy | The ISCAN RK-826PCI binocular tracking system (Burlington, MA) will be used used to objectively record horizontal vergence eye movements. Five parameters will be measured with this instrument and a secondary outcome measures will be the change in accuracy for 4° symmetrical convergence steps | After 12 weeks of therapy | 
| Change in settling time for 4° symmetrical convergence steps after 12 weeks of therapy | The ISCAN RK-826PCI binocular tracking system (Burlington, MA) will be used used to objectively record horizontal vergence eye movements. Five parameters will be measured with this instrument and a secondary outcome measures will be the change in settling time for 4° symmetrical convergence steps | After 12 weeks of therapy | 
| Change in the near point of convergence | The near point of convergence will be measured using the Near Point Rule at baseline and after 12 weeks of therapy. The change in this measurement will a secondary clinical outcome measure. | After 12 weeks of therapy | 
| Change in the positive fusional vergence | Positive fusional vergence will be measured using a handheld target placed 40 cm from the participant and using a horizontal prism bar. Positive fusional vergence will be measured at baseline and after 12 weeks of therapy. The change in this measurement will a secondary clinical outcome measure. | After 12 weeks of therapy |