Establishing New Treatment Approaches for Amblyopia: Perceptual Learning and Video Games

Study Overview
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Brief Summary
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Amblyopia, a developmental abnormality that impairs spatial vision, is a major cause of vision loss, resulting in reduced visual acuity and reduced sensitivity to contrast. This study uses psychophysical measures to study neural plasticity in both adults and children with amblyopia.

Detailed Description
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Amblyopia, a developmental abnormality that impairs spatial vision, is a major cause of vision loss, resulting in reduced visual acuity and reduced sensitivity to contrast. Our previous findings (see Publications) show that the adult amblyopic brain is still plastic and malleable, suggesting that active approach is potential useful in treating amblyopia.The goal of this project is to assess the limits and mechanisms of neural plasticity in both normal and amblyopic spatial vision. This study uses psychophysical measures to study neural plasticity in both adults and children with amblyopia. Research participants will be asked to practice a visual discrimination task (perceptual learning) or to play video games with the amblyopic eye for a period of time. A range of visual functions will be monitored during the course of treatment.

Official Title
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Improving Normal and Amblyopic Vision With Video Games and Perceptual Learning

Conditions
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Amblyopia

Intervention / Treatment
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* Behavioral: Video Game Vision Training
* Behavioral: Perceptual Learning
* Behavioral: Occlusion Therapy


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: adults and children with normal vision or amblyopia amblyopia: interocular VA difference of 0.1 logMAR or more Exclusion Criteria: any ocular pathological conditions, nystagmus
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: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Video Games<br>Participants will be required to play video games for a period of time: 1-2 hrs per session, 4-5 sessions/week for  1-6 months | Behavioral: Video Game Vision Training<br>* A new approach for improving amblyopic vision using video games<br>|
| Experimental: Perceptual learning<br>Participants will be required to practice a visual discrimination task (e.g. visual acuity, position acuity, contrast sensitivity, & stereoacuity) for a period of time: 1-2 hrs per session, 4-5 sessions/week for  1-6 months | Behavioral: Perceptual Learning<br>* A new approach for improving amblyopic vision with perceptual learning<br>|
| Active Comparator: Occlusion therapy<br>Participants will be required to cover the dominant eye during the day in order to push the brain to use the fellow amblyopic eye: 1-2 hrs per session, 4-5 sessions/week for  1-6 months | Behavioral: Occlusion Therapy<br>* Conventional treatment for amblyopia<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in visual acuity before and after the intervention | Visual acuity, the gold standard for vision testing, will be measured. Participants will be asked to read letters on a LogMAR letter chart. The smallest letters that can be read correspond to visual acuity (e.g., Snellen acuity of 20/20, letter-stroke width = 1 minute of arc). | 9 months | 
| Change in stereoacuity before and after the intervention | Stereoacuity will be measured psychophysically using a new stereoacuity function test (1.25, 2.5, 5, 10, 15, & 20 cycles per degree) developed in our previous studies (Li et al 2016). A custom-built 4-mirror haploscope will be used to present a stereogram to each eye. Stereoacuity is the smallest stereo disparity that can be seen in binocular vision (in the unit of seconds of arc, arcsec). The conventional stereoacuity tests (including Randot Stereoacuity Test, Stereofly Test & Preschool Stereo Test) will also be used to measure stereoacuity. Participants will be asked to wear a pair of 3D glasses and to identify the target 3D pictures at various 3D levels. The smallest 3D disparities that can be seen correspond to stereoacuity (e.g. normal range of stereoacuity: 50 seconds of arc or better). | 9 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in contrast sensitivity before and after the intervention | Contrast sensitivity, the ability to detect low contrast / brightness, will be measured psychophysically for a range of spatial frequencies (1.25, 2.5, 5, 10, & 20 cycles per degree). Visual stimuli at different contrast levels will be displayed on a monitor screen. The smallest detectable stimulus contrast level will be measured in the unit of cd/m2. | 9 months | 
| Change in positional (or Vernier) acuity before and after the intervention | Positional acuity, the ability to detect a subtle positional offset between visual stimuli, will be measured psychophysically. Visual stimuli with different amount of positional offsets will be displayed on a monitor screen. The smallest detectable stimulus offset will be measured as position acuity, in the unit of seconds of arc. | 9 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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perceptual learning, video games, visual plasticity, amblyopia treatment, pathophysiology of amblyopia, vision training, stereoacuity, strabismus