Combining Noninvasive Brain Stimulation and Augmented Reality-based Dichoptic Therapy for Treating Amblyopic Adults

The goal of this clinical trial is to learn whether adding noninvasive brain stimulation to augmented reality-based vision therapy can improve vision in adults aged 18 to 40 years with unilateral anisometropic amblyopia, commonly called "lazy eye." Anisometropic amblyopia develops during childhood when the two eyes have different focusing powers and the brain relies more on one eye than the other.

The main questions this study aims to answer are:

• Does active high-definition transcranial direct current stimulation (HD-tDCS) improve best-corrected visual acuity in the amblyopic eye and depth perception more than sham stimulation?
• Does the combined treatment improve contrast sensitivity, suppression between the eyes, and measures of retinal and visual brain function?

All participants will receive the same augmented reality-based dichoptic therapy. This therapy presents different visual information to each eye and lowers the contrast seen by the stronger eye. This gives the weaker, amblyopic eye a visual advantage and encourages both eyes to work together while participants carry out normal daily activities.

During the first 2 weeks, participants will also receive either active HD-tDCS or sham stimulation immediately before the augmented reality therapy. Active HD-tDCS delivers a weak electrical current through small electrodes placed on the scalp. Sham stimulation uses the same equipment and procedures, but the current is applied only briefly at the beginning. Comparing the two groups will help researchers determine whether active brain stimulation provides additional benefits beyond those of augmented reality therapy alone.

Participants will:

• Complete 40-minute augmented reality therapy sessions four times per week for 10 weeks.
• Receive eight 20-minute sessions of active or sham HD-tDCS during the first 2 weeks, immediately before the augmented reality therapy.
• Attend assessment visits before treatment, after 2 weeks, and after 10 weeks. These visits will include vision tests, retinal imaging, tests of retinal function, and brain imaging.