Non-invasive Induction of Metaplasticity to Treat Amblyopia in Adolescent and Adult Patients
Trial Snapshot
- Phase
- Not Applicable
- Status
- Not yet recruiting
- Sponsor
- Boston Children's Hospital
- Enrollment
- 10
- Primary Endpoint
- Amblyopic Eye Best-Corrected Visual Acuity (BCVA)
Study Overview
Brief Summary
The goal of this clinical trial is to determine the efficacy of flicker therapy as an adjunct therapy to treat amblyopia beyond the critical period in adolescents and adults aged 14-40 years who have amblyopia of ≥3 lines of interocular best-corrected (with glasses) visual acuity difference.
The main questions it aims to answer are:
- Does flicker therapy enable clinically meaningful and durable visual recovery from amblyopia?
- Do flicker therapy-treated patients show a change in amblyopic eye visual acuity (lines)? Participants will undergo daily flicker therapy for 1 hour per day.
Detailed Description
The study is a prospective, single arm, open-label, dose-escalation, pilot trial to evaluate the efficacy of daily flicker exposure for the treatment of residual amblyopia in patients 14-40 years of age. Amblyopia, the leading cause of monocular visual impairment in children, is responsive to early interventions such as patching and pharmacologic penalization; however, many patients remain with residual visual deficits despite treatment. Current approaches are limited by age-dependent declines in cortical plasticity after closure of the visual system's "critical period."
Flicker therapy is a new concept, most notably being investigated in the realm of Alzheimer's Disease (AD) to assess cognitive improvements and as a treatment for insomnia. Recent preclinical testing in rodents has shown that metaplasticity can be non-invasively "tuned" by light flickering at different frequencies to encourage different forms of synaptic plasticity in the cerebral cortex, including modifications that enable recovery of function, offering an unprecedented opportunity for amblyopia care. Translational work has further shown that flicker therapy can reopen critical periods in humans, as evidenced by the slowdown of cognitive decline in adult AD subjects, and improved sleep quality in insomniac children. Together, these data provide strong proof-of-concept support for repurposing flicker therapy as a treatment for amblyopia by reactivating plasticity mechanisms rather than targeting neuromodulatory pathways alone.
In this study, 10 subjects with residual amblyopia (best-corrected amblyopic eye visual acuity 20/40-20/400, stable over ≥8 weeks) will receive the VistaSync Visual Stimulation System VTX100, a device which provides the flicker therapy, to use for one hour each day. After the initial phase, subjects will be evaluated for any visual acuity changes. Dose escalation up to 2 hours/day will be permitted at interim visits if insufficient visual improvement is observed without adverse effects.
The primary endpoint is change in visual acuity in the amblyopic eye after 8 weeks of treatment. Secondary endpoints include the proportion of patients achieving resolution of amblyopia, change in stereoacuity, durability of treatment response after cross-over, visual acuity in the fellow eye, and prospective evaluation of the flicker therapy safety profile in this population.
Subjects will be monitored closely through a structured schedule of phone calls and in-person visits over 12 weeks. Safety assessments include symptom surveys. Standardized visual acuity and stereoacuity testing will be performed at each visit. Compliance will be tracked using device logs and investigator assessments.
Study Design
- Study Type
- Interventional
- Allocation
- Na
- Intervention Model
- Single Group
- Primary Purpose
- Treatment
- Masking
- None
Eligibility Criteria
- Ages
- 14 Years to 40 Years (Child, Adult)
- Sex
- All
- Accepts Healthy Volunteers
- No
Inclusion Criteria
- •Age ≥14 and ≤40 years
- •Amblyopia associated with strabismus and/or anisometropia
- •Criteria for strabismus: must meet at least one of the following: heterotropia at distance and/or near with or without spectacle correction, history of strabismus surgery, documented history of strabismus that is no longer present and felt by the investigator could have caused the amblyopia
- •Criteria for anisometropia: must meet at least one of the following:
- •≥ 0.50 D difference in spherical equivalent between eyes
- •≥ 1.50 D difference in astigmatism in any meridian between the eyes
- •Visual acuity measured in each eye within 7 days prior to enrollment using ETDRS protocol on a study certified visual acuity tester as follows:
- •Amblyopic eye visual acuity of 20/40 - 20/400
- •Fellow eye visual acuity of ≥ 20/
- •Spectacle correction for measurement of enrollment visual acuity must meet the following criteria and be based on a cycloplegic refraction < 6 months old:
- •Requirement for spectacle correction:
- •Spherical equivalent must be within 0.50 D of fully correcting anisometropia
- •Hyperopia ≥ 3.00 D must be corrected
- •Hyperopia may not be under-corrected by >1.50 D spherical equivalent and must be symmetrically reduced in each eye
- •Cylinder power must be within 0.50 D of fully correcting the astigmatism
- •Cylinder axis must be within 6 degrees of the axis when the cylinder power is ≥ 1.00 D
- •Myopia of the amblyopic eye >0.50 D spherical equivalent must be corrected
- •Myopia may not be under-corrected by >0.25 D or overcorrected by > 0.50D
- •Spectacles meeting the above criteria must be worn until visual acuity in amblyopic eye has not improved ≥ 1 line (5 letters) by the same testing method during 2 consecutive visual acuity measurements at least 4 weeks apart (i.e. minimum of 12 weeks spectacle correction)
- •Dilated eye examination within 6 months prior to enrollment
- •Subject must be available for at least 4 months of follow-up, have access to a phone, and be willing to be contacted
- •By investigator judgment, the subject is likely to comply with prescribed treatment (i.e. no prior history of poor compliance) and complete all follow up visits
Exclusion Criteria
- •Myopia > -6.00 D spherical equivalent
- •Presence of associated findings that could cause reduced visual acuity
- •Nystagmus does not exclude the subject if the above visual acuity criteria are met
- •Treatment with topical atropine within the past 12 weeks
- •Previous intraocular or refractive surgery
- •Strabismus surgery planned within 16 weeks
- •Current vision therapy or orthoptics
- •History of seizures
- •Known past or present susceptibility to seizures at the discretion of the investigator
- •Known past or present psychological problems
- •Known contraindications or inability to use of a head-mounted device (over one's glasses) and/or exposure to flickering light
- •Current use of medication for the treatment of seizures, bipolar disorder, or migraine
- •Use of any medication with neuromodulatory effects, including
- •Medications that reduce seizure thresholds
Arms & Interventions
Arm 1 - Flicker Therapy
Participants will be required to use the VistaSync Visual Stimulation System VTX100 for 1 hours daily throughout the 8-week study period. At the mid-point 4-week study visit, the dose may be escalated to 2 hours daily, as investigator sees fit. This regimen aims to improve visual acuity in the amblyopic eye by encouraging its use. Compliance with the this protocol will be monitored, and participants will be provided with instructions and support to ensure proper device usage and adherence to the treatment.
Intervention: Flicker (Device)
Outcomes
Primary Outcomes
Amblyopic Eye Best-Corrected Visual Acuity (BCVA)
Time Frame: From enrollment to the end of treatment at 8 weeks
Change in visual acuity of the amblyopic eye after 8 weeks of flicker treatment
Secondary Outcomes
- Proportion of patients with resolved amblyopia(8 weeks)
- Durability of amblyopic eye visual acuity response(From end of treatment at 8 weeks to end of follow-up at 16 weeks)
- Change in stereoacuity(8 weeks and 16 weeks)
- Quality of life measures using the Amblyopia & Strabismis Questionnaire(Change from baseline at 8 weeks and 16 weeks)
- Tolerability and Safety of Flicker Therapy(Assessed throughout the study duration at 1,2, 4, 6, 8, 9, 10, 12, 14 and 16 weeks)
Investigators
Eric Gaier
Assistant Professor of Ophthalmology
Boston Children's Hospital