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

Sponsor

University of Chile (Other)

Overall Status

Terminated

CT.gov ID

NCT05016830

Collaborator

(none)

Enrollment

Location

Arms

2.9

Actual Duration (Months)

4.2

Patients Per Site Per Month

Study Details

Study Description

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.

Condition or Disease	Intervention/Treatment	Phase
Amblyopia	Device: Bilateral transcranial direct current stimulation	N/A

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 Design

Study Type:

Interventional

Actual Enrollment :

12 participants

Allocation:

Randomized

Intervention Model:

Parallel Assignment

Intervention Model Description:

A randomized, controlled pilot trial, that consists in two groups: a control group that receives sham stimulation and ocular occlusion, and a second group that receives bilateral transcranial direct current stimulation and ocular occlusion.A randomized, controlled pilot trial, that consists in two groups: a control group that receives sham stimulation and ocular occlusion, and a second group that receives bilateral transcranial direct current stimulation and ocular occlusion.

Masking:

Triple (Participant, Care Provider, Outcomes Assessor)

Masking Description:

Both sham and bilateral transcranial direct current stimulation were applied with the same electrode configuration, but the functioning of the stimulation device was blinded to the patient, the care provider, and the researcher performing measurements. The operator of the stimulation device selected the stimulation protocol. Sham stimulation protocol consisted of current ramp and delivery of current for 30 seconds and 19 minutes and 30 seconds with no current delivery. Actual stimulation consisted of a current ramp and 20 minutes of current delivery. There were no visual cues allowing to differentiate sham and stimulation protocols.

Primary Purpose:

Treatment

Official Title:

Effect of the Combination of tDCS and Visual Occlusion Therapy on Visual Acuity, Contrast Vision and Depth Vision, in Adult Patients With Amblyopia

Actual Study Start Date :

Nov 5, 2019

Actual Primary Completion Date :

Jan 31, 2020

Actual Study Completion Date :

Jan 31, 2020

Arms and Interventions

Arm	Intervention/Treatment
Sham Comparator: Sham 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.	Device: Bilateral transcranial direct current stimulation A direct current is applied with two electrodes (cathode and anode) in specific parts of the skull. In this case the anode was over the occipital area to target the amblyopic cortex, while the cathode was over the contralateral side, targeting the fellow cortex.
Experimental: 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.	Device: Bilateral transcranial direct current stimulation A direct current is applied with two electrodes (cathode and anode) in specific parts of the skull. In this case the anode was over the occipital area to target the amblyopic cortex, while the cathode was over the contralateral side, targeting the fellow cortex.

Arm

Intervention/Treatment

Sham Comparator: Sham 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.

Device: Bilateral transcranial direct current stimulation

A direct current is applied with two electrodes (cathode and anode) in specific parts of the skull. In this case the anode was over the occipital area to target the amblyopic cortex, while the cathode was over the contralateral side, targeting the fellow cortex.

Experimental: 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.

Device: Bilateral transcranial direct current stimulation

Outcome Measures

Primary Outcome Measures

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.
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 evoked potentials [1-2 hours]
The electroencephalographic response from the primary visual cortex to a stimuli. Measured in millivolts (mV).

Eligibility Criteria

Criteria

Ages Eligible for Study:

18 Years to 65 Years

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

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

Contacts and Locations

Locations

	Site	City	State	Country	Postal Code
1	Faculty of Medicine of University of Chile	Santiago	Region Metropolitana	Chile	8380453

Sponsors and Collaborators

University of Chile

Investigators

Principal Investigator: Romulo A Fuentes Flores, PhD, University of Chile

Study Documents (Full-Text)

None provided.

More Information

Publications

None provided.

Responsible Party:

Romulo Antonio Fuentes Flores, Assistant Professor at Department of Neuroscience, and Director of Research at the Faculty of Medicine of University of Chile, University of Chile

ClinicalTrials.gov Identifier:

NCT05016830

Other Study ID Numbers:

CECI-HCUCH Nº44-2019

First Posted:

Aug 23, 2021

Last Update Posted:

Aug 23, 2021

Last Verified:

Aug 1, 2021

Individual Participant Data (IPD) Sharing Statement:

Plan to Share IPD:

Studies a U.S. FDA-regulated Drug Product:

Studies a U.S. FDA-regulated Device Product:

Product Manufactured in and Exported from the U.S.:

Keywords provided by Romulo Antonio Fuentes Flores, Assistant Professor at Department of Neuroscience, and Director of Research at the Faculty of Medicine of University of Chile, University of Chile

Lazy eye syndrome

Transcranial direct current stimulation

Ocular occlusion

Amblyopia

Additional relevant MeSH terms:

Amblyopia

Study Results

No Results Posted as of Aug 23, 2021