Characteristics of the Vergence Responses of Binocularly Normal Subjects After a Vision Therapy Protocol

Study Overview
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Brief Summary
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A vision therapy protocol for vergence ability is mentioned. The purpose of this study is to evaluate objectively the change in the vergence responses of binocular and accommodative normal subjects after performing a classic vision therapy protocol. This study is an interventional, cross-over, and randomized study.

Detailed Description
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After the first evaluation, subjects will be classified in the Experimental Group (EG) or Control Group (CG) randomly. There will be 18 subjects in each group. A classic vision therapy protocol for fusional vergence will be performed in the EG and the CG will be doing a placebo therapy, based on studies done before. The EG will do weekly office-based therapy of 45 minutes during 12 weeks and the CG will do weekly office-based placebo therapy of 15 minutes during 12 weeks. This placebo therapy will consist of smooth-pursuit and discrimination exercises that do not influence vergence response. The office-based done by the EG consists of a vergence therapy and its protocol will follow Scheiman's indications protocol. This vision therapy will train both positive and negative fusional vergence amplitudes in the same proportion. A pre-evaluation, a during evaluation, and a post-evaluation will be done at weeks 1, 6, and 12 respectively to all subjects. After the post-evaluation week, the CG will do 12 weeks more of office-based therapy but, this group will do the same conventional vergence protocol as EG. The CG will be evaluated at week 18, and finally, at week 24. During the evaluations, the vergence eye movements will be measured during the positive and negative fusional vergence tests. The break and the recovery points will be evaluated to all the subjects with three different methods performed in a randomized order: (1) objective computer-based test in the haploscopic system, (2) prism bar, and (3) phoropter rotary prisms. All these tests will be performed at 40 cm with a classic central visual target. This study aims to evaluate objectively the change in the vergence responses of binocular and accommodative normal subjects after performing a classic vision therapy protocol.

Official Title
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Evaluate Objectively the Change in the Vergence Responses of Binocular and Accommodative Normal Subjects After Performing a Classic Vision Therapy Protocol

Conditions
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Vision Disorders, Eye; Movement Disorder (Binocular), Vision Therapy, Binocular Vision Disorder

Intervention / Treatment
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* Other: Experimental: Classical Vision Therapy Treatment
* Other: Control: Eye Movement Therapy Treatment


Participation Criteria
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Eligibility Criteria
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Normal binocular and accommodative subjects will participate in the study. All subjects have to fulfill the inclusion criteria. All evaluations will consist of the following objective and subjective optometric tests, which will be executed for all participants. Monocular and binocular VA at near and distance with their habitual correction Refractive error measured with the Grand Seiko WAM-5500 Autorefractor Cover Test at near (40 cm) Near Point of Accommodation Near Point of Convergence Vergence Facility Test at near (40 cm) Monocular and binocular Accommodation Facility Test at near (40 cm) Negative and Positive Relative Accommodation Test (ARN and ARP) Random Dot 2 Stereo acuity Test CISS questionnaire Fusional Vergence Amplitude using both subjective and objective methods Exclusion Criteria: having eye surgery having an eye pathology having a binocular or an accommodative disorder using orto-K lenses

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 30 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
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Classical Vision Therapy Treatment: vision therapy exercises for fusional vergence abilities<br>The Experimental Group (EG) it consist in a Classical Vision Therapy Treatment. This group will do weekly office-based therapy of 45 minutes of visual exercises during 12 weeks. The office-based done by the EG consists of a vergence therapy and its protocol will follow Scheiman's Protocol and Indications. The exercises do not tough the eye or use drugs. They are just visual training exercises that improve fusional convergence and divergence response. | Other: Experimental: Classical Vision Therapy Treatment<br>* Do classical vision therapy treatment for improve vergence<br>* Other names: Vision therapy protocol;|
| Placebo Comparator: Eye Movement Therapy Treatment: vision therapy placebo exercises not improve fusional vergence<br>The Control Group or Placebo Group consist in a Control: Eye Movement Therapy Treatment. This group will do weekly office-based placebo therapy of 15 minutes during 12 weeks of visual exercises. This placebo therapy will consist of smooth-pursuit and discrimination exercises that do not influence vergence response. The exercises do not tough the eye nor use drugs. They are just visual training exercises that do not improve fusional vergence response as they improve smooth-pursuit eye movements. | Other: Experimental: Classical Vision Therapy Treatment<br>* Do classical vision therapy treatment for improve vergence<br>* Other names: Vision therapy protocol;Other: Control: Eye Movement Therapy Treatment<br>* Do eye movement therapy treatment in order not to improve vergence<br>* Other names: Vision therapy protocol;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Objective vergence response: To evaluate objectively the change in positive and negative fusional vergence at near of binocularly and accommodative normal subjects after performing a vision therapy | It is measured objectively with an haparoscopic setup and eye movements were recorded with an Eyelink 1000 Plus (SR Research) at 500Hz. Firstly, stimulus disparity changed smoothly at 1PD/s up to 45PD for both divergence (BI) and convergence (BO), mimicking a Risley prism. Secondly, the disparity was changed in steps of 2PD mimicking a prism bar. Break and recovery points were determined offline using a custom Matlab code for the analysis of eye movements. Measurements will be compared before and after the therapy treatment. | Through study completion, an average of 6 months | 
| Subjective vergence response: To evaluate objectively the change in positive and negative fusional vergence at near of binocularly and accommodative normal subjects after performing a vision therapy | It is evaluated with the clinical methods measured subjectively using the Risley prism of the phoropter and the Prism Bar. Measurements will be compared before and after the therapy treatment. | Through study completion, an average of 6 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Vergence, Vision Therapy, Binocular Vision