The goal of this randomized controlled trial is to investigate the effectiveness of non-invasive brain stimulation in treating adults with amblyopia. The main questions it aims to answer are: 1. What are the effects of non-invasive brain stimulation on neuronal plasticity in the visual cortex of adults with amblyopia, and does it produce lasting changes? 2. Do cumulative sessions of non-invasive brain stimulation influence neural plasticity and higher-order visual functions in adults with amblyopia? The investigators hypothesize that non-invasive brain stimulation will show a positive cumulative effect after five (5) consecutive days of stimulation on visual perception and function in adults with amblyopia. Participants will be randomized into one of two treatment groups: 1. High-frequency transcranial random noise stimulation (hf-tRNS). 2. Sham stimulation. Researchers will compare baseline measurements of crowded visual acuity, contrast sensitivity, stereoacuity, phosphene thresholds, global motion perception, form pattern recognition and pattern-reversal visual evoked potentials (VEPs) to post-treatment measurements for each group.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
60
Sham transcranial random noise stimulation will be applied over the primary visual cortex (area V1) with the current ramping up for 20 seconds before ramping down for 20 seconds. The 2.0 milliamp current stimulation will occur for only a few seconds at the start and at the end of the 40 minutes.
Non-invasive brain stimulation will involve the use of high-frequency transcranial random noise stimulation (100-640 Hz) to apply a 2.0 milliamp current over the primary visual cortex (area V1) for approximately 40 minutes with a ramp up to the maximum programmed current and ramp down of 20 seconds.
Midwestern University Eye Institute
Downers Grove, Illinois, United States
RECRUITINGCrowded Visual Acuity
A change in crowded visual acuity is measured in LogMAR from baseline.
Time frame: Pre- and post-treatment (Days 1-5); 24-hour follow-up (Day 6); 72-hour follow-up (Day 8); and 10-day follow-up (Day 15).
Stereo Acuity
A change in stereo acuity is measured in arc seconds from baseline.
Time frame: Pre- and post-treatment (Days 1-5); 24-hour follow-up (Day 6); 72-hour follow-up (Day 8); and 10-day follow-up (Day 15).
Phosphene Threshold
A change in phosphene threshold (%) from baseline.
Time frame: Pre- and post-treatment (Days 1-5); 24-hour follow-up (Day 6); 72-hour follow-up (Day 8); and 10-day follow-up (Day 15).
Global Motion Perception
A change in global motion perception coherence threshold (%) from baseline.
Time frame: Pre- and post-treatment (Days 1-5); 24-hour follow-up (Day 6); 72-hour follow-up (Day 8); and 10-day follow-up (Day 15).
Form Pattern Recognition
A change in form pattern recognition coherence threshold (%) from baseline.
Time frame: Pre- and post-treatment (Days 1-5); 24-hour follow-up (Day 6); 72-hour follow-up (Day 8); and 10-day follow-up (Day 15).
Pattern-reversal Visual Evoked Potentials (pVEP)
A change in N75-P100 amplitudes and P100 latencies from baseline.
Time frame: Pre-treatment (Day 1); post-treatment (Day 5); 24-hour follow-up (Day 6); 72-hour follow-up (Day 8); and 10-day follow-up (Day 15).
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