Recruiting

Observational Study

Sponsor:

Centre for Eye and Vision Research

Code:

NCT05394987

Conditions

Amblyopia

Eligibility Criteria

Sex: All

Age: 18 - 39

Healthy Volunteers: Accepted

Interventions

Spectacles

Study Details

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

Study ID

NCT05394987

Start date

Jun 13, 2022

Status verified date

Mar, 2026

Completion date

May 31, 2027

Anticipated

Primary completion date

Nov 30, 2026

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18 - 39

Healthy Volunteers: Accepted

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

Study Design

Enrollment

36 participants

Anticipated

Intervention Model

Single group

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: Optical correction

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

Interventions

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.

Primary outcome measure

  • Best corrected visual acuity of the amblyopic eye pre-intervention [ Time Frame: Approx. 5 mins, baseline (day 1 of spectacle wear) ]
  • Best corrected visual acuity of the amblyopic eye post-intervention [ Time Frame: Approx. 5 mins, on completion of study (week 24) ]

Central Contacts and Locations

Central contacts

Benjamin Thompson, PhD

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

Ken WS Tan, PhD

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

Locations

University of Waterloo

Recruiting

Waterloo, Ontario, Canada, N2L 3G1

Contacts

Benjamin Thompson, PhD

+1519-888-4567ben.thompson@uwaterloo.ca

More Information

Sponsor

Centre for Eye and Vision Research

Last update posted

Mar 18, 2026

Last verified

Mar, 2026

Keywords

  • Amblyopia
  • Binocular vision
  • Suppression
  • Plasticity
  • Optical correction

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by Centre for Eye and Vision Research on 2026-03-18.