Optical Correction and Visual Functions of Adults With Amblyopia

Amblyopia Clinical Trial

— SPECTRA  

Official title:

Spectacle Correction for the Treatment of Amblyopia

Clinical Trial Details — Status: Recruiting

Administrative data

• NCT number: NCT05394987
• Other study ID #: SPECTRA
• Status: Recruiting
• Phase: N/A
• Start date: June 13, 2022
• Est. completion date: May 31, 2027

Study information

• Verified date: June 2024
• Source: Centre for Eye and Vision Research
• Contact: Benjamin Thompson, PhD
• Phone: +852-3169-9631
• Email: ben.thompson[@]cevr.hk
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial 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.

Recruitment information / eligibility

• Status: Recruiting
• Enrollment: 36
• Est. completion date: May 31, 2027
• Est. primary completion date: November 30, 2026
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 18 Years to 39 Years

Eligibility

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 prescribed refractive correction in spectacles (e.g., due to aniseikonia)

• Contraindication to cycloplegic eye drops

• Currently under amblyopia treatment/therapy

• Inability to comprehend test instructions and/or provide consent

• Eccentric fixation

• >-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) psychiatric, visual, or neurological disorders

Related Conditions & MeSH terms

• Amblyopia

Intervention

Device:
• Spectacles
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.

Locations

Country	Name	City	State
Canada	University of Waterloo	Waterloo	Ontario
Hong Kong	Centre for Eye and Vision Research Limited	Hong Kong	Guangdong

Sponsors (3)

Lead Sponsor	Collaborator
Centre for Eye and Vision Research	The Hong Kong Polytechnic University, University of Waterloo

Countries where clinical trial is conducted

Canada,  Hong Kong, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Other	Electrical potentials pre-intervention	Electroencephalography (EEG) measures: Visual evoked potentials for high and low contrast stimuli (monocular: fellow eye and amblyopic eye)	Approx. 60 mins, baseline (day 1 of spectacle wear)
Other	Electrical potentials post-intervention	Electroencephalography (EEG) measures: Visual evoked potentials for high and low contrast stimuli (monocular: fellow eye and amblyopic eye)	Approx. 60 mins, on completion of study (week 24)
Other	Electrical potentials during intervention	Electroencephalography (EEG) measures: Visual evoked potentials for high and low contrast stimuli (monocular: fellow eye and amblyopic eye)	Approx. 60 mins, 12 weeks from baseline (day 1 of spectacle wear)
Primary	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)
Primary	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	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
Secondary	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)
Secondary	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)
Secondary	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
Secondary	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)
Secondary	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)
Secondary	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
Secondary	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)
Secondary	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)
Secondary	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
Secondary	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)
Secondary	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)
Secondary	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
Secondary	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)
Secondary	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)
Secondary	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
Secondary	Amblyopic eye contrast sensitivity pre-intervention	Computer-based measurement of contrast sensitivity	Approx. 10 mins, baseline (day 1 of spectacle wear)
Secondary	Amblyopic eye contrast sensitivity post-intervention	Computer-based measurement of contrast sensitivity	Approx. 10 mins, on completion of study (week 24)
Secondary	Amblyopic eye contrast sensitivity during intervention	Computer-based measurement of contrast sensitivity	Approx. 10 mins, every 4 weeks from start of intervention
Secondary	Stereopsis pre-intervention	Smallest disparity on the Randot preschool test reported accurately.	Approx. 5 mins, baseline (day 1 of spectacle wear)
Secondary	Stereopsis post-intervention	Smallest disparity on the Randot preschool test reported accurately.	Approx. 5 mins, on completion of study (week 24)
Secondary	Stereopsis during intervention	Smallest disparity on the Randot preschool test reported accurately.	Approx. 5 mins, every 4 weeks from start of intervention
Secondary	Angle of strabismus pre-intervention	Prismatic power required to neutralise the angle of deviation on alternating prism cover test.	Approx. 5 mins,baseline (day 1 of spectacle wear)
Secondary	Angle of strabismus post-intervention	Prismatic power required to neutralise the angle of deviation on alternating prism cover test.	Approx. 5 mins, on completion of study (week 24)
Secondary	Angle of strabismus during intervention	Prismatic power required to neutralise the angle of deviation on alternating prism cover test.	Approx. 5 mins, every 4 weeks from start of intervention
Secondary	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)
Secondary	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)
Secondary	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
Secondary	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)
Secondary	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)
Secondary	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
Secondary	Interocular suppression pre-intervention	Computer-based measurement of interocular suppression.	Approx. 10 mins, baseline (day 1 of spectacle wear)
Secondary	Interocular suppression post-intervention	Computer-based measurement of interocular suppression.	Approx. 10 mins, on completion of study (week 24)
Secondary	Interocular suppression during intervention	Computer-based measurement of interocular suppression.	Approx. 10 mins, every 4 weeks from start of intervention
Secondary	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)
Secondary	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)