Optical Correction and Visual Functions of Adults With Amblyopia

NCT ID: NCT05394987

Last Updated: 2024-06-14

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

RECRUITING

Clinical Phase

NA

Total Enrollment

36 participants

Study Classification

INTERVENTIONAL

Study Start Date

2022-06-13

Study Completion Date

2027-05-31

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.

Detailed Description

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Conditions

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Amblyopia

Study Design

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Allocation Method

NA

Intervention Model

SINGLE_GROUP

Within-subject, pre-post interventional study, measuring the effect of optical correction on visual function.
Primary Study Purpose

TREATMENT

Blinding Strategy

NONE

Study Groups

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Optical correction

Prescription of spectacles for full-time wear to correct refractive error

Group Type EXPERIMENTAL

Spectacles

Intervention Type DEVICE

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.

Interventions

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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.

Intervention Type DEVICE

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 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
Minimum Eligible Age

18 Years

Maximum Eligible Age

39 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes

Sponsors

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The Hong Kong Polytechnic University

OTHER

Sponsor Role collaborator

University of Waterloo

OTHER

Sponsor Role collaborator

Centre for Eye and Vision Research

OTHER

Sponsor Role lead

Responsible Party

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Responsibility Role SPONSOR

Principal Investigators

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Benjamin Thompson, PhD

Role: PRINCIPAL_INVESTIGATOR

Centre for Eye and Vision Research Limited

Ken WS Tan, PhD

Role: STUDY_DIRECTOR

Centre for Eye and Vision Research Limited

Locations

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University of Waterloo

Waterloo, Ontario, Canada

Site Status RECRUITING

Centre for Eye and Vision Research Limited

Hong Kong, Guangdong, Hong Kong

Site Status RECRUITING

Countries

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Canada Hong Kong

Central Contacts

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Benjamin Thompson, PhD

Role: CONTACT

+852-3169-9631

Ken WS Tan, PhD

Role: CONTACT

+852-3169-9631

Facility Contacts

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Benjamin Thompson, PhD

Role: primary

+1519-888-4567 ext. x39398

Peter CK Pang, PhD

Role: primary

+852-2766-7927

References

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Tan KWS, Park ASY, Cheung BWS, Wong GHT, Thompson B; SPECTRA study team. SPEctacle Correction for the TReatment of Amblyopia (SPECTRA): study protocol for a prospective non-randomised interventional trial in adults with anisometropic/mixed mechanism amblyopia. BMJ Open. 2024 Jul 1;14(6):e080151. doi: 10.1136/bmjopen-2023-080151.

Reference Type DERIVED
PMID: 38950991 (View on PubMed)

Other Identifiers

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SPECTRA

Identifier Type: -

Identifier Source: org_study_id

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