SPECTRA: Optical Correction and Visual Functions of Adults With Amblyopia
Study Details
Study Description
Brief Summary
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.
| Condition or Disease | Intervention/Treatment | Phase |
|---|---|---|
|
N/A |
Study Design
Arms and Interventions
| Arm | Intervention/Treatment |
|---|---|
| Experimental: Optical correction Prescription of spectacles for full-time wear to correct refractive error |
Device: Spectacles
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.
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Outcome Measures
Primary Outcome Measures
- Best corrected visual acuity of the amblyopic eye pre-intervention [Approx. 5 mins, baseline (day 1 of spectacle wear)]
The size of the smallest line of letters read accurately on an ETDRS chart.
- Best corrected visual acuity of the amblyopic eye post-intervention [Approx. 5 mins, on completion of study (week 24)]
The size of the smallest line of letters read accurately on an ETDRS chart.
Secondary Outcome Measures
- Best corrected visual acuity of the amblyopic eye during intervention [Approx. 5 mins, every 4 weeks from start of intervention]
The size of the smallest line of letters read accurately on an ETDRS chart.
- Fellow eye distance visual acuity pre-intervention [Approx. 5 mins, baseline (day 1 of spectacle wear)]
The size of the smallest line of letters read accurately on an ETDRS chart.
- Fellow eye distance visual acuity post-intervention [Approx. 5 mins, on completion of study (week 24)]
The size of the smallest line of letters read accurately on an ETDRS chart.
- Fellow eye distance visual acuity during-intervention [Approx. 5 mins, every 4 weeks from start of intervention]
The size of the smallest line of letters read accurately on an ETDRS chart.
- Binocular distance visual acuity pre-intervention [Approx. 5 mins, baseline (day 1 of spectacle wear)]
The size of the smallest line of letters read accurately on an ETDRS chart.
- Binocular distance visual acuity post-intervention [Approx. 5 mins, on completion of study (week 24)]
The size of the smallest line of letters read accurately on an ETDRS chart.
- Binocular distance visual acuity during intervention [Approx. 5 mins, every 4 weeks from start of intervention]
The size of the smallest line of letters read accurately on an ETDRS chart.
- Near visual acuity of amblyopic eye pre-intervention [Approx. 5 mins, baseline (day 1 of spectacle wear)]
The size of the smallest line of letters read accurately on a near ETDRS chart.
- Near visual acuity of amblyopic eye post-intervention [Approx. 5 mins, on completion of study (week 24)]
The size of the smallest line of letters read accurately on a near ETDRS chart.
- Near visual acuity of amblyopic eye during intervention [Approx. 5 mins,every 4 weeks from start of intervention]
The size of the smallest line of letters read accurately on a near ETDRS chart.
- Near visual acuity of fellow eye pre-intervention [Approx. 5 mins, baseline (day 1 of spectacle wear)]
The size of the smallest line of letters read accurately on a near ETDRS chart.
- Near visual acuity of fellow eye post-intervention [Approx. 5 mins, on completion of study (week 24)]
The size of the smallest line of letters read accurately on a near ETDRS chart.
- Near visual acuity of fellow eye during intervention [Approx. 5 mins, every 4 weeks from start of intervention]
The size of the smallest line of letters read accurately on a near ETDRS chart.
- Near binocular visual acuity pre-intervention [Approx. 5 mins, baseline (day 1 of spectacle wear)]
The size of the smallest line of letters read accurately on a near ETDRS chart.
- Near binocular visual acuity post-intervention [Approx. 5 mins, on completion of study (week 24)]
The size of the smallest line of letters read accurately on a near ETDRS chart.
- Near binocular visual acuity during intervention [Approx. 5 mins, every 4 weeks from start of intervention]
The size of the smallest line of letters read accurately on a near ETDRS chart.
- Amblyopic eye contrast sensitivity pre-intervention [Approx. 10 mins, baseline (day 1 of spectacle wear)]
Computer-based measurement of contrast sensitivity
- Amblyopic eye contrast sensitivity post-intervention [Approx. 10 mins, on completion of study (week 24)]
Computer-based measurement of contrast sensitivity
- Amblyopic eye contrast sensitivity during intervention [Approx. 10 mins, every 4 weeks from start of intervention]
Computer-based measurement of contrast sensitivity
- Stereopsis pre-intervention [Approx. 5 mins, baseline (day 1 of spectacle wear)]
Smallest disparity on the Randot preschool test reported accurately.
- Stereopsis post-intervention [Approx. 5 mins, on completion of study (week 24)]
Smallest disparity on the Randot preschool test reported accurately.
- Stereopsis during intervention [Approx. 5 mins, every 4 weeks from start of intervention]
Smallest disparity on the Randot preschool test reported accurately.
- Angle of strabismus pre-intervention [Approx. 5 mins,baseline (day 1 of spectacle wear)]
Prismatic power required to neutralise the angle of deviation on prism cover test (cover/uncover test).
- Angle of strabismus post-intervention [Approx. 5 mins, on completion of study (week 24)]
Prismatic power required to neutralise the angle of deviation on prism cover test (cover/uncover test).
- Angle of strabismus during intervention [Approx. 5 mins, every 4 weeks from start of intervention]
Prismatic power required to neutralise the angle of deviation on prism cover test (cover/uncover test).
- Amblyopic eye fixation stability pre-intervention [Approx. 5 mins, baseline (day 1 of spectacle wear)]
Eye position recorded with high-speed eye tracker during fixation as quantified by bivariate contour ellipse area (BCEA).
- Amblyopic eye fixation stability post-intervention [Approx. 5 mins, on completion of study (week 24)]
Eye position recorded with high-speed eye tracker during fixation as quantified by bivariate contour ellipse area (BCEA).
- Amblyopic eye fixation stability during intervention [Approx. 5 mins, every 4 weeks from start of intervention]
Eye position recorded with high-speed eye tracker during fixation as quantified by bivariate contour ellipse area (BCEA).
- Fellow (non-amblyopic) eye fixation stability pre-intervention [Approx. 5 mins, baseline (day 1 of spectacle wear)]
Eye position recorded with high-speed eye tracker during fixation as quantified by bivariate contour ellipse area (BCEA).
- Fellow (non-amblyopic) eye fixation stability post-intervention [Approx. 5 mins, on completion of study (week 24)]
Eye position recorded with high-speed eye tracker during fixation as quantified by bivariate contour ellipse area (BCEA).
- Fellow (non-amblyopic) eye fixation stability during intervention [Approx. 5 mins, every 4 weeks from start of intervention]
Eye position recorded with high-speed eye tracker during fixation as quantified by bivariate contour ellipse area (BCEA).
- Interocular suppression pre-intervention [Approx. 10 mins, baseline (day 1 of spectacle wear)]
Computer-based measurement of interocular suppression.
- Interocular suppression post-intervention [Approx. 10 mins, on completion of study (week 24)]
Computer-based measurement of interocular suppression.
- Interocular suppression during intervention [Approx. 10 mins, every 4 weeks from start of intervention]
Computer-based measurement of interocular suppression.
- Quality of life pre-intervention [Approx.15-20 mins, baseline (day 1 of spectacle wear)]
Questionnaire scores for: Amblyopia and Strabismus Questionnaire World Health Organization Quality of Life-BREF
- Quality of life post-intervention [Approx. 15-20 mins, on completion of study (week 24)]
Questionnaire scores for: Amblyopia and Strabismus Questionnaire World Health Organization Quality of Life-BREF
Other Outcome Measures
- Electrical potentials pre-intervention [Approx. 60 mins, baseline (day 1 of spectacle wear)]
Electroencephalography (EEG) measures: Visual evoked potentials for high and low contrast stimuli (monocular and binocular) Resting state potentials
- Electrical potentials post-intervention [Approx. 60 mins, on completion of study (week 24)]
Electroencephalography (EEG) measures: Visual evoked potentials for high and low contrast stimuli (monocular and binocular) Resting state potentials
- Electrical potentials during intervention [Approx. 60 mins, 12 weeks from baseline (day 1 of spectacle wear)]
Electroencephalography (EEG) measures: Visual evoked potentials for high and low contrast stimuli (monocular and binocular) Resting state potentials
Eligibility Criteria
Criteria
Inclusion Criteria:
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18-39 (inclusive) years of age
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Anisometropic amblyopia (difference of ≥0.50D spherical equivalent or ≥1.50D astigmatism between eyes) or mixed mechanism amblyopia (strabismus and anisometropia)
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Best corrected visual acuity (BCVA) in the amblyopic eye of 0.3 logMAR to 1.0 logMAR (inclusive)
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BCVA in the non-amblyopic eye of 0.1 logMAR or better, and an interocular VA difference of 2 logMAR lines or more
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Difference of 1.00D or more between current refractive correction and study prescription
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Good general health
Exclusion Criteria:
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Other pathological ocular anomalies known to cause reduced visual acuity
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Presbyopia (based on amplitude of accommodation)
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Inability to tolerate full refractive correction in spectacles (e.g., due to aniseikonia)
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Contraindication to cycloplegic eye drops (only when necessary for assessing residual refractive error)
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Currently under amblyopia treatment/therapy
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Inability to comprehend test instructions and/or provide consent
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Eccentric fixation and/or abnormal retinal correspondence
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-6.00DS of myopia in either eye with spectacles
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Bilateral amblyopia
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Presence of amblyopia that is not due to strabismus and/or anisometropia
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Presence of (current or previous) attention disorder, learning disability, psychiatric, visual, or neurological disorders
Contacts and Locations
Locations
| Site | City | State | Country | Postal Code | |
|---|---|---|---|---|---|
| 1 | Centre for Eye and Vision Research Limited | Hong Kong | Guangdong | Hong Kong | 00000 |
Sponsors and Collaborators
- Centre for Eye and Vision Research
- The Hong Kong Polytechnic University
- University of Waterloo
Investigators
- Principal Investigator: Benjamin Thompson, PhD, Centre for Eye and Vision Research Limited
- Study Director: Ken WS Tan, PhD, Centre for Eye and Vision Research Limited
Study Documents (Full-Text)
None provided.More Information
Publications
None provided.- SPECTRA