Optical Correction and Visual Functions of Adults With Amblyopia
ConditionAmblyopia
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age18-39
SponsorCentre for Eye and Vision Research
About this trial
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.
Eligibility criteria
This trial accepts healthy volunteersQualifiers
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
Disqualifiers
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
Trial design
Design model
Single group
Treatments tested in this trial
Spectacles
DevicePrescription 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.
Treatment groups
36 Participants
are divided into 1 treatment groupGroup A: Optical correctionExperimental treatment 1 intervention
Trial outcomes
Primary outcomes
1
Best 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)2
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)Secondary outcomes
1
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 intervention2
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)3
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)4
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 interventionOther outcomes
1
Electrical potentials pre-intervention
Electroencephalography (EEG) measures: Visual evoked potentials for high and low contrast stimuli (monocular: fellow eye and amblyopic eye)
Time frame
Approx. 60 mins, baseline (day 1 of spectacle wear)2
Electrical potentials post-intervention
Electroencephalography (EEG) measures: Visual evoked potentials for high and low contrast stimuli (monocular: fellow eye and amblyopic eye)
Time frame
Approx. 60 mins, on completion of study (week 24)3
Electrical potentials during intervention
Electroencephalography (EEG) measures: Visual evoked potentials for high and low contrast stimuli (monocular: fellow eye and amblyopic eye)
Time frame
Approx. 60 mins, 12 weeks from baseline (day 1 of spectacle wear)Sponsors and contacts
Click on the lead sponsor to view all of their trials.
Centre for Eye and Vision Research
Lead sponsor
The Hong Kong Polytechnic University
Collaborator
University of Waterloo
Collaborator
Source ClinicalTrials.gov