Evaluation of Amblyopia Protocols Using a Dichoptic Gabor Videogame Program

Study Overview
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Brief Summary
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Interest in developing alternative methods for the treatment of amblyopia (lazy eye) has long been a topic of interest among clinicians and researchers. Occlusion or penalization of fellow eye do not always provide the desired visual acuity improvement. Moreover, occlusion is associated with a high risk of recurrence and non-compliance. Here, it is presented a protocol of a randomized clinical trial to evaluate the safety and clinical efficacy of a novel home-based system, based on a computer game. The goal of this prospective clinical trial is to compare in visual acuity improvements in patients with amblyopia, following conventional patching therapy or this novel computer-based therapy. The main questions it aims to answer are: Does computer-based therapy equal or improve patching therapy? Can it be used as an alternative to patching? Does computer-based therapy used in combination with pathching solve amblyopia when patching fails alone (persistent amblyopia)? Participants will be divided in two groups according to the previous occlusion o penalization of fellow eye. Both groups will be divided in two subgroups, experimental and control. Researchers will compare subgroups outcomes in order to asses this novel approach.

Detailed Description
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Amblyopia is a common neurodevelopmental abnormality that results in physiological alterations of the visual pathways and impaired vision in one eye or, less commonly, in both.Disruption of normal visual development early in life may result in perceptual, oculomotor and clinical abnormalities such as instability of fixation, anomalous retinal correspondence, and lack of stereoacuity.Amblyopia has a prevalence of around 2-4% in children and is associated with refractive error (anisometropia or isometropia) and strabismus. The Pediatric Eye Disease Investigator Group (PEDIG) has produced several studies that analyze the most effective therapies for amblyopic eye. The gold standard treatment prescribed for this condition combines spectacle correction of the refractive error with penalization and/or occlusion of the dominant eye Interest in developing alternative methods for the treatment of amblyopia (lazy eye) has long been a topic of interest among clinicians and researchers. Occlusion or penalization of fellow eye do not always provide the desired visual acuity improvement. Moreover, occlusion is associated with a high risk of recurrence and non-compliance. This randomized clinical trial is designed to evaluate the safety and clinical efficacy of a novel home-based system, based on a computer activity that uses dichoptic Gabor Patches and band-filtered noise masks. It combines the concepts of perceptual learning, dichoptic training, home based therapy and gamification. The goal of this prospective clinical trial is to compare in visual acuity improvements in patients with amblyopia, following conventional patching therapy or this novel computer-based therapy. The main questions it aims to answer are: Does computer-based therapy equal or improve patching therapy? Can it be used as an alternative to patching? Does computer-based therapy used as coadjuvant to pathching solve amblyopia in patients where patching fails alone (persistent amblyopia)? Participants will be divided in two groups according to the previous occlusion o penalization of fellow eye. Both groups will be divided in two subgroups, experimental and control. Researchers will compare subgroups outcomes in order to asses if this novel approach may lead to greater improvements in vision performance in amblyopic children as substitution of occlusion treatment in novel amblyopia or as coadjutant in persistent amblyopia.

Official Title
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Randomized Controlled Trial of a Dichoptic Gabor Videogame Program to Improve Visual Function in Children With Amblyopia

Conditions
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Amblyopia

Intervention / Treatment
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* Device: Visionary: computer exercises using dichoptic Gabor Patches and band-filtered noise masks
* Device: Patching


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: The sample will be made up of children with amblyopia from 4 to 12 years old (amblyopia will be defined as the best corrected visual acuity less o equal to 0.8 in decimal units or > 2 lines of difference between both eyes). Strabismus inclusion criteria will be < 25 prismatic diopters, with a deviation ≥ 2 prismatic diopters. Exclusion Criteria: Subjects with nystagmus, ocular pathology o cognitive delay will be excluded.

Ages Eligible for Study
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Minimum Age: 4 Years
Maximum Age: 12 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
Interventional Model Description: Participants will be divided in two groups: GA, 60 participants without previous occlusion treatment; GB, 60 participants with previous occlusion or penalization. In GA, participants will be assigned to an Experimental subgroup (GA-E) or to a Control subgroup (GA-C). GA-E volunteers will be prescribed computer-based exercises (Visionary). GA-C patients will be prescribed occlusion. In GB, all participants will receive occlusion. There will be two subgroups, Experimental (GB-E) and Control (GB-C), and both will be prescribed exercises using Visionary. In GB-E the computer will adjust Gabor patches frequency to visual acuity, as normal; but in GB-C Gabor frequencies will always be low. Importantly, those patients with deviations (10 to 25 prismatic diopters) will be assigned to experimental or treatment subgroups following an independent randomization.
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Group GA-E. Patients without previous occlusion o penalization treatment - Experimental<br>GA-E volunteers (experimental) will be prescribed home therapy using computer-based exercises (Visionary) for 12 weeks, five days week, ½ half hour per day. Visionary target frequencies will be adjusted, considering BCVA, each three weeks. Contrast of Gabor patch frequencies will be adjusted to match patient contrast sensitivity thresholds. In case BCVA does not improve at least 2 lines in two consecutive visits (6 weeks), patients will change to GA-C. | Device: Visionary: computer exercises using dichoptic Gabor Patches and band-filtered noise masks<br>* Visionary exercises are computer gammified activities that run on a computer with internet connection to facilitate home therapy. Patient must wear anaglyph glasses. Visual stimuli consists in dichoptic Gabor Patches presented to the amblyopic eye. Frequency is adjusted to actual patient visual acuity, and contrast to actual patient performance (contrast sensitivity). A band-filtered noise mask at the same frequency than the Gabor patch is presented to the fellow eye in certain ocassions.<br>|
| Active Comparator: Group GA-C. Patients without previous occlusion o penalization treatment - Control<br>GA-C patients (control) will be prescribed occlusion following Pediatric Eye Disease Investigation Group (PEDIG) criteria: 2 hours for mild and moderate amblyopia or 6 hours for severe amblyopia. Patients will receive a calendar to track patching accomplishment. In case BCVA does not improve at least 2 lines in two consecutive visits (6 weeks), patients will change to GA-E. | Device: Patching<br>* PEDIG (Pediatric Eye Disease Investigator Group) recommended amblyopia treatment. Consist on covering a child's better-seeing eye with a patch for 2 hours per day for mild and moderate amblyopia or 6 hours per day for severe amblyopia<br>|
| Experimental: Group GB-E. Patients with previous occlusion o penalization treatment - Experimental<br>GB-E volunteers will receive occlusion following PEDIG criteria and will be prescribed home therapy using Visionary. Patients will receive a calendar to track patching accomplishment. Visionary target frequencies will be adjusted, considering BCVA, each three weeks. | Device: Visionary: computer exercises using dichoptic Gabor Patches and band-filtered noise masks<br>* Visionary exercises are computer gammified activities that run on a computer with internet connection to facilitate home therapy. Patient must wear anaglyph glasses. Visual stimuli consists in dichoptic Gabor Patches presented to the amblyopic eye. Frequency is adjusted to actual patient visual acuity, and contrast to actual patient performance (contrast sensitivity). A band-filtered noise mask at the same frequency than the Gabor patch is presented to the fellow eye in certain ocassions.<br>Device: Patching<br>* PEDIG (Pediatric Eye Disease Investigator Group) recommended amblyopia treatment. Consist on covering a child's better-seeing eye with a patch for 2 hours per day for mild and moderate amblyopia or 6 hours per day for severe amblyopia<br>|
| Active Comparator: Group GB-C. Patients with previous occlusion o penalization treatment - Control<br>GB-C volunteers will receive occlusion following PEDIG criteria and will be prescribed home therapy using Visionary. Patients will receive a calendar to track patching accomplishment. Visionary target frequencies will always be low, no matter patient VA. In case BCVA does not improve at least 2 lines in two consecutive visits (6 weeks), patients will be move to GB-E. | Device: Visionary: computer exercises using dichoptic Gabor Patches and band-filtered noise masks<br>* Visionary exercises are computer gammified activities that run on a computer with internet connection to facilitate home therapy. Patient must wear anaglyph glasses. Visual stimuli consists in dichoptic Gabor Patches presented to the amblyopic eye. Frequency is adjusted to actual patient visual acuity, and contrast to actual patient performance (contrast sensitivity). A band-filtered noise mask at the same frequency than the Gabor patch is presented to the fellow eye in certain ocassions.<br>Device: Patching<br>* PEDIG (Pediatric Eye Disease Investigator Group) recommended amblyopia treatment. Consist on covering a child's better-seeing eye with a patch for 2 hours per day for mild and moderate amblyopia or 6 hours per day for severe amblyopia<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| BCVA Best Corrected Visual Acuity | Best Corrected Visual Acuity is the measurement of the ability to distinguish shapes and the details of objects at a given distance wearing full refraction. Different optotipes are used to measure clinically this ability (e.g. Snellen E, ETDRS, etc.). Refraction must be calculated under cyclopegia following PEDIG criteria. Crowding bars can be added to the optotypes. In this study, amblyopic eye BCVA will be measured using visual acuity chart ETDRS whitout crowding bars, in logarithmic scale. | Treatment will last 12 weeks, with BCVA measurements every 2 weeks. The stability control post treatment will last 12 months, with BCVA controls at 3, 6 and 12 months. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Stereoacuity | In this stuty Randot Preschool Stereoacuity Test (Stereo Optical, Inc., Chicago, USA) will be used to asses stereoacuity in arc seconds. This is a random dot stereogram that measures global stereopsis (or cyclopean stereopsis) and does not contain monocular cues. Stereoacuity is measured at a constant distance of 40 cm. | Treatment will last 12 weeks, with stereoacuity measurements every 2 weeks. The stability control post treatment will last 12 months, with stereoacuity controls at 3, 6 and 12 months. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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amblyopia, perceptual learning, dichoptic therapy, visual acuity