Optical Correction and Visual Functions of Adults With Amblyopia

Study Overview
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Brief Summary
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Amblyopia is a developmental anomaly resulting from abnormal visual experiences in early life. Amblyopia causes reduced visual acuity in the absence of a pathology. Adult sensory systems are believed to be structurally invariant beyond early, critical periods of development. However, recent evidence suggest that visual functions in adults with amblyopia can be improved with optical correction alone. This study aims to investigate whether improvements in best corrected visual acuity and other visual functions can result following appropriate optical correction in adults with amblyopia. Functional measures relating to vision, binocular vision, and eye movements will be used to assess the efficacy of refractive correction for improving vision. This study will help us better understand the improvements in visual functions following optical correction, as well as the mechanisms underlying neuroplasticity in adults with amblyopia.

Official Title
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Spectacle Correction for the Treatment of Amblyopia

Conditions
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Amblyopia

Intervention / Treatment
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* Device: Spectacles


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 18-39 (inclusive) years of age Anisometropic amblyopia (difference of ≥0.50D spherical equivalent or ≥1.50D astigmatism between eyes) or mixed mechanism amblyopia (strabismus and anisometropia) Best corrected visual acuity (BCVA) in the amblyopic eye of 0.3 logMAR to 1.0 logMAR (inclusive) BCVA in the non-amblyopic eye of 0.1 logMAR or better, and an interocular VA difference of 2 logMAR lines or more Difference of 1.00D or more between current refractive correction and study prescription Good general health Exclusion Criteria: Other pathological ocular anomalies known to cause reduced visual acuity Presbyopia (based on amplitude of accommodation) Inability to tolerate full refractive correction in spectacles (e.g., due to aniseikonia) Contraindication to cycloplegic eye drops (only when necessary for assessing residual refractive error) Currently under amblyopia treatment/therapy Inability to comprehend test instructions and/or provide consent Eccentric fixation and/or abnormal retinal correspondence >-6.00DS of myopia in either eye with spectacles Bilateral amblyopia Presence of amblyopia that is not due to strabismus and/or anisometropia Presence of (current or previous) attention disorder, learning disability, psychiatric, visual, or neurological disorders

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 39 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: Within-subject, pre-post interventional study, measuring the effect of optical correction on visual function.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Optical correction<br>Prescription of spectacles for full-time wear to correct refractive error | Device: Spectacles<br>* Prescription of refractive error correction in spectacles. Refractive error will be determined as part of a standard optometric eye exam (performed by a registered optometrist). Guidelines for optical correction for the prescription of the study spectacles (based on Pediatric Eye Disease Investigator Group [PEDIG] amblyopia clinical trial protocols): Hypermetropia - not under-corrected by more than +1.50D spherical equivalent and the reduction in plus sphere must be identical between the two eyes. Anisometropia - full correction of the anisometropic difference. Astigmatism - full cylinder power prescribed. Appropriate refractive error correction will be prescribed. Participants will be instructed to wear the optical correction full-time (i.e., more than 50% of waking hours) for the duration of the study.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Best corrected visual acuity of the amblyopic eye pre-intervention | The size of the smallest line of letters read accurately on an ETDRS chart. | Approx. 5 mins, baseline (day 1 of spectacle wear) | 
| Best corrected visual acuity of the amblyopic eye post-intervention | The size of the smallest line of letters read accurately on an ETDRS chart. | Approx. 5 mins, on completion of study (week 24) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Best corrected visual acuity of the amblyopic eye during intervention | The size of the smallest line of letters read accurately on an ETDRS chart. | Approx. 5 mins, every 4 weeks from start of intervention | 
| Fellow eye distance visual acuity pre-intervention | The size of the smallest line of letters read accurately on an ETDRS chart. | Approx. 5 mins, baseline (day 1 of spectacle wear) | 
| Fellow eye distance visual acuity post-intervention | The size of the smallest line of letters read accurately on an ETDRS chart. | Approx. 5 mins, on completion of study (week 24) | 
| Fellow eye distance visual acuity during-intervention | The size of the smallest line of letters read accurately on an ETDRS chart. | Approx. 5 mins, every 4 weeks from start of intervention | 
| Binocular distance visual acuity pre-intervention | The size of the smallest line of letters read accurately on an ETDRS chart. | Approx. 5 mins, baseline (day 1 of spectacle wear) | 
| Binocular distance visual acuity post-intervention | The size of the smallest line of letters read accurately on an ETDRS chart. | Approx. 5 mins, on completion of study (week 24) | 
| Binocular distance visual acuity during intervention | The size of the smallest line of letters read accurately on an ETDRS chart. | Approx. 5 mins, every 4 weeks from start of intervention | 
| Near visual acuity of amblyopic eye pre-intervention | The size of the smallest line of letters read accurately on a near ETDRS chart. | Approx. 5 mins, baseline (day 1 of spectacle wear) | 
| Near visual acuity of amblyopic eye post-intervention | The size of the smallest line of letters read accurately on a near ETDRS chart. | Approx. 5 mins, on completion of study (week 24) | 
| Near visual acuity of amblyopic eye during intervention | The size of the smallest line of letters read accurately on a near ETDRS chart. | Approx. 5 mins,every 4 weeks from start of intervention | 
| Near visual acuity of fellow eye pre-intervention | The size of the smallest line of letters read accurately on a near ETDRS chart. | Approx. 5 mins, baseline (day 1 of spectacle wear) | 
| Near visual acuity of fellow eye post-intervention | The size of the smallest line of letters read accurately on a near ETDRS chart. | Approx. 5 mins, on completion of study (week 24) | 
| Near visual acuity of fellow eye during intervention | The size of the smallest line of letters read accurately on a near ETDRS chart. | Approx. 5 mins, every 4 weeks from start of intervention | 
| Near binocular visual acuity pre-intervention | The size of the smallest line of letters read accurately on a near ETDRS chart. | Approx. 5 mins, baseline (day 1 of spectacle wear) | 
| Near binocular visual acuity post-intervention | The size of the smallest line of letters read accurately on a near ETDRS chart. | Approx. 5 mins, on completion of study (week 24) | 
| Near binocular visual acuity during intervention | The size of the smallest line of letters read accurately on a near ETDRS chart. | Approx. 5 mins, every 4 weeks from start of intervention | 
| Amblyopic eye contrast sensitivity pre-intervention | Computer-based measurement of contrast sensitivity | Approx. 10 mins, baseline (day 1 of spectacle wear) | 
| Amblyopic eye contrast sensitivity post-intervention | Computer-based measurement of contrast sensitivity | Approx. 10 mins, on completion of study (week 24) | 
| Amblyopic eye contrast sensitivity during intervention | Computer-based measurement of contrast sensitivity | Approx. 10 mins, every 4 weeks from start of intervention | 
| Stereopsis pre-intervention | Smallest disparity on the Randot preschool test reported accurately. | Approx. 5 mins, baseline (day 1 of spectacle wear) | 
| Stereopsis post-intervention | Smallest disparity on the Randot preschool test reported accurately. | Approx. 5 mins, on completion of study (week 24) | 
| Stereopsis during intervention | Smallest disparity on the Randot preschool test reported accurately. | Approx. 5 mins, every 4 weeks from start of intervention | 
| Angle of strabismus pre-intervention | Prismatic power required to neutralise the angle of deviation on prism cover test (cover/uncover test). | Approx. 5 mins,baseline (day 1 of spectacle wear) | 
| Angle of strabismus post-intervention | Prismatic power required to neutralise the angle of deviation on prism cover test (cover/uncover test). | Approx. 5 mins, on completion of study (week 24) | 
| Angle of strabismus during intervention | Prismatic power required to neutralise the angle of deviation on prism cover test (cover/uncover test). | Approx. 5 mins, every 4 weeks from start of intervention | 
| Amblyopic eye fixation stability pre-intervention | Eye position recorded with high-speed eye tracker during fixation as quantified by bivariate contour ellipse area (BCEA). | Approx. 5 mins, baseline (day 1 of spectacle wear) | 
| Amblyopic eye fixation stability post-intervention | Eye position recorded with high-speed eye tracker during fixation as quantified by bivariate contour ellipse area (BCEA). | Approx. 5 mins, on completion of study (week 24) | 
| Amblyopic eye fixation stability during intervention | Eye position recorded with high-speed eye tracker during fixation as quantified by bivariate contour ellipse area (BCEA). | Approx. 5 mins, every 4 weeks from start of intervention | 
| Fellow (non-amblyopic) eye fixation stability pre-intervention | Eye position recorded with high-speed eye tracker during fixation as quantified by bivariate contour ellipse area (BCEA). | Approx. 5 mins, baseline (day 1 of spectacle wear) | 
| Fellow (non-amblyopic) eye fixation stability post-intervention | Eye position recorded with high-speed eye tracker during fixation as quantified by bivariate contour ellipse area (BCEA). | Approx. 5 mins, on completion of study (week 24) | 
| Fellow (non-amblyopic) eye fixation stability during intervention | Eye position recorded with high-speed eye tracker during fixation as quantified by bivariate contour ellipse area (BCEA). | Approx. 5 mins, every 4 weeks from start of intervention | 
| Interocular suppression pre-intervention | Computer-based measurement of interocular suppression. | Approx. 10 mins, baseline (day 1 of spectacle wear) | 
| Interocular suppression post-intervention | Computer-based measurement of interocular suppression. | Approx. 10 mins, on completion of study (week 24) | 
| Interocular suppression during intervention | Computer-based measurement of interocular suppression. | Approx. 10 mins, every 4 weeks from start of intervention | 
| Quality of life pre-intervention | Questionnaire scores for: Amblyopia and Strabismus Questionnaire World Health Organization Quality of Life-BREF | Approx.15-20 mins, baseline (day 1 of spectacle wear) | 
| Quality of life post-intervention | Questionnaire scores for: Amblyopia and Strabismus Questionnaire World Health Organization Quality of Life-BREF | Approx. 15-20 mins, on completion of study (week 24) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Amblyopia, Binocular vision, Suppression, Plasticity, Optical correction