None listed
Conditions
Brief summary
Amblyopia, also known as lazy eye, is a developmental disorder of vision whereby the brain ignores the information from one eye. This leads to a reduction in the vision of that eye. Also, the two eyes fail to work together resulting in a lack of binocular vision. Anisometropia is a significant difference in focusing between the two eyes caused by underlying anatomical factors. Significant anisometropia limits binocular co-operation and is a well known cause of amblyopia either alone or in combination with a strabismus /misalignment of one eye. The defocus caused by anisometropia is corrected using corrective lenses but image size differences (aniseikonia) also caused by anisometropia are often ignored. This study is designed to investigate whether correcting for image size difference as well as image defocus, during the initial glasses only phase will reduce the need for the eye to ignore the information from one eye and improve treatment outcomes for these patients.
Interventions
Participants will be provided with aniseikonia-correcting lenses to be worn for the optical treatment of their anisometropic amblyopia. These spectacle lenses are designed to equalise focus and also reduce aniseikonia (image size differences) between the two eyes. Correction will be administered by clinically qualified and registered orthoptists and optometrists who are named study investigators. Participants will be required to wear their allocated glasses full time (at least 75% of waking hour
Participants will be provided with aniseikonia-correcting lenses to be worn for the optical treatment of their anisometropic amblyopia. These spectacle lenses are designed to equalise focus and also reduce aniseikonia (image size differences) between the two eyes. Correction will be administered by clinically qualified and registered orthoptists and optometrists who are named study investigators. Participants will be required to wear their allocated glasses full time (at least 75% of waking hours) for 15 weeks. Compliance with glasses wear will be monitored through a daily glasses wear dairy that will take less than 5mins to complete each day (for the parent). No other vision therapy will be administered during the intervention period.
Sponsors
The University Of Auckland
Study design
Allocation
Randomised controlled trial
Intervention model
Parallel
Primary purpose
Treatment
Masking
Blinded (masking used) (Subject, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
All
Age
4 Years to 8 Years
Healthy volunteers
No
Inclusion criteria
• 4-8 Years of age • Anisometropia equal to or greater than 1.50 DS difference in spherical equivalent between eyes • Uncorrected Vision in the worst eye of 6/12 (0.30 logMAR) or worse with an interocular difference of 2 lines or more. Visual acuity will be measured using the ATS-HOTV protocol on the Electronic Visual Acuity tester (EVA). • No manifest strabismus at near or distance on cover test • Refractive corrections meet the following criteria and are based on a cycloplegic refraction that is not more than six months old. The criteria are: 1) Hyperopia: not be under-corrected by more than +1.50D spherical equivalent and the reduction in plus sphere must be identical between the two eyes. 2) Anisometropia: full correction of the anisometropic difference. 3) Astigmatism: full cylindrical power will be prescribed. 4) Cylinder axis in the spectacle lenses in both eyes must be equal to or less than +/-6 degrees of the axis of the cycloplegic refraction when cylinder power is equal to or greater than 1.00 D. • Willing and being able to provide written informed consent for participation in the study
Exclusion criteria
Presence of a constant or alternating strabismus at any distance, previous amblyopia treatment, Myopia > 6.00D, previous intraocular surgery, any co-existent ocular pathology and any known neurological conditions. Not willing to wear spectacle refractive correction
Outcome results
None listed