Bilateral Transcranial Direct Current Stimulation and Ocular Occlusion for Adults With Amblyopia

Not Applicable

Terminated

• Conditions: Amblyopia
• Interventions: Device: Bilateral transcranial direct current stimulation

• Registration Number: NCT05016830
• Lead Sponsor: University of Chile

Brief Summary

A prospective interventional study is expected to be conducted, to test a possible new treatment for amblyopia (lazy eye syndrome). Bilateral transcranial direct current stimulation (tDCS) is a type of noninvasive brain stimulation, which may help in visual function recovery of adult patients with amblyopia. This pilot study will test the feasibility of said therapy, along with the short term effects of bilateral tDCS in visual function.

Detailed Description

Theoretical Framework: Ocular occlusion treatment has been used classically and with excellent results for the treatment of amblyopia in those under 14 years of age, since in this period it has been seen that there is greater neuroplasticity, leaving little to do in the period of lower neuroplasticity, in young and adult patients with later diagnoses. Transcranial Direct Current Stimulation therapy is an emergent technique used in neurological diseases to increase neuroplasticity, by changing the resting potential of neurons. Our hypothesis is that the combination of tDCS and visual occlusion therapy is capable of increasing visual acuity, contrast sensitivity, and depth perception, in young people over 18 years of age.

Methodology: The application of a double-blind, randomized clinical trial is proposed to evaluate the application of 2 different therapies: Occlusion with bilateral tDCS, and Occlusion with tDCS sham (sham). The study subjects will be randomly assigned to a group, and one session of stimulation will be performed. Data will be analyzed using Student's t test, or Mann-Whitney test, according to the normal or non-normal distribution of the sample, respectively. Also, the change over time of the variables will be measured using the Conditional Change Model.

Expected Results: The investigators expect that visual acuity, contrast vision, and dichoptic vision in the Occlusion therapy group with bilateral tDCS will be significantly higher than the Occlusion therapy group with tDCS sham (sham).

Study Timeline

• Study Start: 2019-11-05
• Primary Completion: 2020-01-31
• Study Completion: 2020-01-31
• Status Verified: 2021-08
• Study First Submitted: 2021-08-13
• Study First Submitted QC: 2021-08-20
• Last Update Submitted: 2021-08-20
• Study First Posted: 2021-08-23
• Last Update Posted: 2021-08-23

Recruitment & Eligibility

• Status: TERMINATED
• Sex: All
• Target Recruitment: 12

Inclusion Criteria

• Prior diagnosis of Amblyopia

Exclusion Criteria

• Ophthalmologic disease other than amblyopia
• Chronic pharmacological therapy
• Implanted medical device
• Neurologic disease or surgery history
• History of an adverse reaction to tDCS
• Pregnancy
• Not able to give informed consent

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Bilateral transcranial direct current stimulation	Bilateral transcranial direct current stimulation	Bilateral transcranial direct current stimulation consisted of 2 mA of current from the anodal electrode in the amblyopic primary visual cortex to the cathodal electrode located in the fellow primary visual cortex and the stimulation was on for 20 minutes. On stimulation onset, the participant's fellow eye was occluded and the participant performed a reading task for 20 minutes.
Sham bilateral transcranial direct current stimulation	Bilateral transcranial direct current stimulation	Sham bilateral transcranial direct current stimulation consisted of 2 milliamperes (mA) of current from the anodal electrode in the amblyopic primary visual cortex to the cathodal electrode located in the fellow primary visual cortex, but the stimulation was turned off after 30 seconds. On Sham Stimulation onset, the participant's fellow eye was occluded and the participant performed a reading task for 20 minutes.

Primary Outcome Measures

Name	Time	Method
Visual evoked potentials	1-2 hours	The electroencephalographic response from the primary visual cortex to a stimuli. Measured in millivolts (mV).
Stereopsis	1-2 hours	the perception of depth produced by the reception in the brain of visual stimuli from both eyes in combination. Measured in degrees of arc.
Visual Acuity	1-2 hours	Clarity or Sharpness in vision, measured in LogMar
Visual Sensitivity	1-2 hours	The ability to perceive differences between an object and its background, measured in percentage of contrast sensitivity.

Trial Locations

Locations (1)

Faculty of Medicine of University of Chile; 🇨🇱 Santiago, Region Metropolitana, Chile