The VIBRANT (Vision Improvement through Behavioral Rehabilitation And Neuroplasticity Training) study is a prospective, double-blind, crossover design (within-subject) in participants with homonymous hemianopia-a type of visual field loss resulting from damage to the post-chiasmatic visual pathways. It aims to investigate whether transcranial random noise stimulation (tRNS) combined with perceptual learning-based training has potential for improving visual impairments.

A. Stroke, brain tumor, or traumatic brain injury patients

Inclusion Criteria:

1. At least 18 years of age.
2. Capable of providing informed consent and complying with study procedures.
3. Unilateral or bilateral focal brain damage causing loss of vision.
4. At least three months post-stroke or traumatic brain injury, or a stable brain tumor within the past year.

Exclusion Criteria:

1. Severe CNS diseases or disorders unrelated to the focal lesion, which could interfere with study results.
2. Severe mental health challenges that could interfere with study results, or current or recent (within the past 6 months) drug or alcohol abuse or addiction as defined by DSM-5.
3. Vision loss resulting from ocular disease or disorder.

B. Healthy volunteers (age-matched controls):

Inclusion Criteria:

1. At least 18 years of age.
2. Capable of providing informed consent and complying with study procedures.

Exclusion Criteria:

1. Any CNS diseases or psychiatric disorders (e.g., epilepsy, schizophrenia) that would interfere with study results.
2. Previous head injury.
3. Present or past (within past 6 months) drug or alcohol abuse or addiction based on DSM-5.

This study is double-blind, meaning that both the participants and the researchers will be blinded to the treatment conditions.