Effectiveness of tDCS in Paediatric Amblyopia. (tDCS)

The goal of this randomized, double-blind clinical trial is to determine whether transcranial direct current stimulation (tDCS) can effectively and safely improve vision in children aged 4-14 years with strabismic or anisometropic amblyopia that has not responded to conventional patching therapy.

The main questions it aims to answer are:

Does tDCS produce significant and sustained improvements in visual acuity, contrast sensitivity, and stereopsis in children with amblyopia?

Is tDCS a safe, well-tolerated, and faster alternative or complementary treatment compared with standard occlusion therapy?

Does tDCS induce functional and structural changes in the visual cortex associated with increased neuroplasticity, including modulation of GABAergic activity?

If there is a comparison group:

Researchers will compare active tDCS with sham (placebo) stimulation to see if active treatment leads to greater visual recovery and cortical changes than placebo.

Participants will:

Receive several sessions of active or sham tDCS using low-intensity electrical stimulation applied to visual brain areas.

Undergo standard visual assessments, including visual acuity, contrast sensitivity, and stereopsis.

Complete neurophysiological and neuroimaging evaluations (EEG, pattern visual evoked potentials, and functional MRI).

Provide biochemical measures related to GABA levels.

This study aims to validate tDCS as a non-invasive, child-friendly, and effective therapy that may overcome the limitations of patching and support its inclusion in paediatric clinical practice.

Study Overview

• Status: Not yet recruiting
• Conditions: Visual Acuity; Amblyopia; Stereoscopic Vision; Amblyopia Strabismic
• Intervention / Treatment: Device: tDCS

Detailed Description

Amblyopia is a neurodevelopmental visual disorder characterised by reduced visual performance despite optimal optical correction and the absence of ocular pathology. It affects up to 2-4% of children and is the leading cause of visual impairment in this population. Conventional treatment involves optical correction and patching of the contralateral (non-amblyopic) eye, which usually produces limited improvement, low therapeutic compliance and frequent relapses, highlighting the need for new approaches based on neuroplasticity.

Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique that can modify cortical excitability by regulating GABAergic inhibition in the primary visual cortex (V1). It has been safely used in children with attention deficit disorder, schizophrenia, epilepsy or cerebral palsy.

Preliminary data from our group show that after three sessions of tDCS on paediatric strabismic amblyopia, there are significant and sustained improvements in visual acuity, contrast sensitivity, and stereopsis at 3 months.

This project proposes a randomised, double-blind clinical trial to evaluate the efficacy, safety and optimal dosage regimen of tDCS in children aged 4 to 14 years with strabismic or anisometropic amblyopia classified as non-responsive to occlusion therapy, according to the criteria established by the Pediatric Eye Disease Investigation Group (PEDIG). Objective biomarkers will be included using electroencephalogram, visual evoked potentials (pattern) and functional magnetic resonance imaging to explore cortical functional and structural changes, together with biochemical assessment of GABA levels.

The expected outcome is to validate tDCS as an effective, rapid, and safe alternative or complementary therapy for amblyopia. Demonstrating sustained visual and cortical improvements would support its inclusion in paediatric clinical protocols and promote translational neuro-ophthalmological rehabilitation

• Study Type: Interventional
• Enrollment (Estimated): 100
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Dr. Francisco Javier Valiente Soriano, Optics and Optometry; Phone Number: +34 670 25 58 48; Email: fjvaliente@um.es

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Children aged 4-14 years.
• Strabismic amblyopia resistant to patching (PEDIG criteria).
• Anisometropic amblyopia resistant to patching (PEDIG criteria).

Exclusion Criteria:

• Ocular pathology.
• Nystagmus.
• Mental disability.
• Cognitive delay.
• Neurological problems incompatible with treatment.
• Pacemakers.
• Intracranial electrodes.
• Implanted defibrillators.
• Cranial pathologies.
• Cranial lesions.
• Withdrawal will occur upon adverse events, protocol deviation, refusal, or loss to follow-up.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Group tDCS; Children aged 4 to 14 with amblyopia treated at one of the collaborating hospitals and centers, with visual acuity in the amblyopic eye between 20/32 and 20/200. They will undergo tests of visual acuity, stereoscopic visual acuity, fixation, and contrast sensitivity. The direct current will be gradually increased over 34 seconds to 2 mA, held constant for 15 minutes, and then gradually reduced to zero using NIC2® v2.1.2.0 software (Neuroelectrics®, Barcelona, Spain). The stimulating current is applied using two rubber electrodes housed in circular sponge pockets (8 cm² each) soaked in saline solution. The electrodes are placed at Oz (active/stimulating electrode, located in the visual cortex) and Cz (reference electrode).	Device: tDCS; The direct current is gradually increased over 34 seconds until it reaches 2 mA, remains constant for 15 minutes, and then is gradually reduced to zero using NIC2® v2.1.2.0 software (Neuroelectrics®, Barcelona, Spain). The stimulating current is applied using two rubber electrodes housed in circular sponge pockets (8 cm² each) soaked in saline solution. The electrodes are placed at Oz (active/stimulating electrode, located in the visual cortex) and Cz (reference electrode). This includes a total of 3 sessions of 15 minutes and 34 seconds separated by 48 hours.
Sham Comparator: Group Sham; The sham group is equipped with the same electrostimulation helmet, but the intensity protocol is set to 0 at all times. The same measurements are taken and exactly the same procedure is followed as with the experimental group.	Device: tDCS; The direct current is gradually increased over 34 seconds until it reaches 2 mA, remains constant for 15 minutes, and then is gradually reduced to zero using NIC2® v2.1.2.0 software (Neuroelectrics®, Barcelona, Spain). The stimulating current is applied using two rubber electrodes housed in circular sponge pockets (8 cm² each) soaked in saline solution. The electrodes are placed at Oz (active/stimulating electrode, located in the visual cortex) and Cz (reference electrode). This includes a total of 3 sessions of 15 minutes and 34 seconds separated by 48 hours.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Visual Acuity	Visual acuity measurements were performed by the same examiner, using a calibrated optotype at a distance of six meters, before starting treatment, after each session, one month after treatment, and three months after treatment.	3 months
Stereoscopic visual acuity	Stereoscopic visual acuity was measured using TNO test (with the butterfly plate corresponding to 1300" and the circular plate to 1200"), the subject places the test 40 cm away and must identify calibrated figures.	3 months
Contrast sensitivity	Contrast sensitivity was measured using CSV-1000 test (3, 6, 12, and 18 cycles per degree). The patient must identify scratched circles whose frequency is decreasing.	3 months
Eye Fixation	Eye fixation was evaluated using the Topcon Macular Integrity Assessment (MAIA) microperimeter (Topcon corporation, Tokyo, Japan), which delineates two distinct regions using 1° (P1) and 2° (P2) circles.	3 months

Collaborators and Investigators

• Sponsor: Universidad de Murcia
• Collaborators: Hospital Universitario Virgen de la Arrixaca; Hospital General Universitario Morales Meseguer; Hospital Universitario Reina Sofia de Cordoba

Study record dates

Study Major Dates

• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): June 30, 2026
• Study Completion (Estimated): August 31, 2029

Study Registration Dates

• First Submitted: April 16, 2026
• First Submitted That Met QC Criteria: April 16, 2026
• First Posted (Actual): April 23, 2026

Study Record Updates

• Last Update Posted (Actual): April 29, 2026
• Last Update Submitted That Met QC Criteria: April 23, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: tDCS; Ambyopia
• Additional Relevant MeSH Terms: Neurologic Manifestations; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Eye Diseases; Vision Disorders; Sensation Disorders; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Amblyopia; Therapeutics; Behavioral Disciplines and Activities; Electric Stimulation Therapy; Convulsive Therapy; Psychiatric Somatic Therapies; Electroshock; Psychological Techniques; Transcranial Direct Current Stimulation
• Other Study ID Numbers: T-TDCS-PJY

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No