Optical Correction and Visual Functions of Adults With Amblyopia

NCT05394987 | Recruiting

• 1 other identifier: SPECTRA
• Study Type: interventional
• Target: 36
• Locations: 2 countries
• Sites: 2

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.

Conditions

Amblyopia

Keywords

Amblyopia; Binocular vision; Suppression; Plasticity; Optical correction

Outcome Measures

Primary Outcomes (2)

• 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 Outcomes (36)

• Best corrected visual acuity of the amblyopic eye during intervention

  Approx. 5 mins, every 4 weeks from start of intervention

• Fellow eye distance visual acuity pre-intervention

  Approx. 5 mins, baseline (day 1 of spectacle wear)

• Fellow eye distance visual acuity post-intervention

  Approx. 5 mins, on completion of study (week 24)

• Fellow eye distance visual acuity during-intervention

  Approx. 5 mins, every 4 weeks from start of intervention

• Binocular distance visual acuity pre-intervention

  Approx. 5 mins, baseline (day 1 of spectacle wear)

Other Outcomes (3)

• Electrical potentials pre-intervention

  Approx. 60 mins, baseline (day 1 of spectacle wear)

• Electrical potentials post-intervention

  Approx. 60 mins, on completion of study (week 24)

• Electrical potentials during intervention

  Approx. 60 mins, 12 weeks from baseline (day 1 of spectacle wear)

Study Arms (1)

Optical correction

EXPERIMENTAL

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

Device: Spectacles

Interventions

Spectacles 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.

Optical correction

Eligibility Criteria

• Age: 18 Years - 39 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• (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

You may not qualify if:

• 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

Sponsors & Collaborators

• Centre for Eye and Vision Research: lead
• The Hong Kong Polytechnic University: collaborator
• University of Waterloo: collaborator

Study Sites (2)

University of Waterloo

Waterloo, Ontario, N2L 3G1, Canada

RECRUITING

Centre for Eye and Vision Research Limited

Hong Kong, Guangdong, 00000, Hong Kong

RECRUITING

Related Publications (1)

• 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.

  PMID: 38950991 DERIVED

MeSH Terms

Conditions

Amblyopia

Interventions

Eyeglasses

Condition Hierarchy (Ancestors)

Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Vision Disorders; Sensation Disorders; Neurologic Manifestations; Eye Diseases; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Intervention Hierarchy (Ancestors)

Lenses; Optical Devices; Equipment and Supplies

Study Officials

• Benjamin Thompson, PhD

  Centre for Eye and Vision Research Limited

  PRINCIPAL INVESTIGATOR

• Ken WS Tan, PhD

  Centre for Eye and Vision Research Limited

  STUDY DIRECTOR

Central Study Contacts

Benjamin Thompson, PhD

CONTACT

+852-3169-9631; ben.thompson@cevr.hk

Ken WS Tan, PhD

CONTACT

+852-3169-9631; ken.tan@cevr.hk

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Within-subject, pre-post interventional study, measuring the effect of optical correction on visual function.

Study Record Dates

• First Submitted: May 19, 2022
• First Posted: May 27, 2022
• Study Start: June 13, 2022
• Primary Completion (Estimated): November 30, 2026
• Study Completion (Estimated): May 31, 2027
• Last Updated: March 18, 2026

Record last verified: 2026-03

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP
• Time Frame: After publication of study results for an indefinite period.
• Access Criteria: Upon reasonable request and approved by the study principal investigator.

Locations

HK (1); CA (1)