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.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
TREATMENT
Masking
NONE
Enrollment
36
Prescription of refractive error correction in spectacles. Refractive error to be determined as part of standard optometric eye exam (performed by 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 undercorrected by \>+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: cylinder power in each eye should be within ≤±0.50D of fully correcting the astigmatism for each eye. If cylinder power is ≥1.00D, the prescribed axis in both eyes should be within ≤±6 deg of the cycloplegic refraction axis. Appropriate refractive error correction will be prescribed. Participants will be instructed to wear the optical correction full-time (i.e., \>50% of waking hours) for the duration of the study.
University of Waterloo
Waterloo, Ontario, Canada
RECRUITINGCentre for Eye and Vision Research Limited
Hong Kong, Guangdong, Hong Kong
RECRUITINGBest corrected visual acuity of the amblyopic eye pre-intervention
The size of the smallest line of letters read accurately on an ETDRS chart.
Time frame: 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.
Time frame: Approx. 5 mins, on completion of study (week 24)
Best corrected visual acuity of the amblyopic eye during intervention
The size of the smallest line of letters read accurately on an ETDRS chart.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: Approx. 5 mins, every 4 weeks from start of intervention
Amblyopic eye contrast sensitivity pre-intervention
Computer-based measurement of contrast sensitivity
Time frame: Approx. 10 mins, baseline (day 1 of spectacle wear)
Amblyopic eye contrast sensitivity post-intervention
Computer-based measurement of contrast sensitivity
Time frame: Approx. 10 mins, on completion of study (week 24)
Amblyopic eye contrast sensitivity during intervention
Computer-based measurement of contrast sensitivity
Time frame: Approx. 10 mins, every 4 weeks from start of intervention
Stereopsis pre-intervention
Smallest disparity on the Randot preschool test reported accurately.
Time frame: Approx. 5 mins, baseline (day 1 of spectacle wear)
Stereopsis post-intervention
Smallest disparity on the Randot preschool test reported accurately.
Time frame: Approx. 5 mins, on completion of study (week 24)
Stereopsis during intervention
Smallest disparity on the Randot preschool test reported accurately.
Time frame: 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 alternating prism cover test.
Time frame: Approx. 5 mins,baseline (day 1 of spectacle wear)
Angle of strabismus post-intervention
Prismatic power required to neutralise the angle of deviation on alternating prism cover test.
Time frame: Approx. 5 mins, on completion of study (week 24)
Angle of strabismus during intervention
Prismatic power required to neutralise the angle of deviation on alternating prism cover test.
Time frame: 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).
Time frame: 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).
Time frame: 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).
Time frame: 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).
Time frame: 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).
Time frame: 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).
Time frame: Approx. 5 mins, every 4 weeks from start of intervention
Interocular suppression pre-intervention
Computer-based measurement of interocular suppression.
Time frame: Approx. 10 mins, baseline (day 1 of spectacle wear)
Interocular suppression post-intervention
Computer-based measurement of interocular suppression.
Time frame: Approx. 10 mins, on completion of study (week 24)
Interocular suppression during intervention
Computer-based measurement of interocular suppression.
Time frame: Approx. 10 mins, every 4 weeks from start of intervention
Quality of life pre-intervention
Questionnaire scores for: 1. Amblyopia and Strabismus Questionnaire 2. World Health Organization Quality of Life-BREF
Time frame: Approx.15-20 mins, baseline (day 1 of spectacle wear)
Quality of life post-intervention
Questionnaire scores for: 1. Amblyopia and Strabismus Questionnaire 2. World Health Organization Quality of Life-BREF
Time frame: Approx. 15-20 mins, on completion of study (week 24)
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