Inclusion Criteria:  Participants must be 19 to 75 years of age, at the time of screening Patients with normal tension glaucoma or open angle glaucoma Patients with best-corrected visual acuity of 20/40 or more Patients whose Mean Deviation(MD) value of visual field test is -6dB or less Patients who have stable eye pressure of less than 20mmHg over the past 2 months If glaucoma treatment is in progress, the type, dose, and form of drug for treatment are stable for more than 2 months  A person who has no pregnancy plan during the clinical trial period and has agreed to an effective contraceptive plan for WOCBP(Women of child bearing potential)  WONCBP(Women of non-child bearing potential) must meet at least one of the following criteria:  Postmenopausal women who are at least 45 years old and had no menses for 24 consecutive months A woman who underwent hysterectomy of bilateral ovarian resection recorded by a doctor All other female patients will be considered WOCBP. A person who voluntarily agreed to participate in this clinical trial  Exclusion Criteria:  Ophthalmological and neurological diseases that can affect visual field test(e.g., optic neuritis, diabetic retinopathy, age-related macular degeneration, and the epiretinal membrane) A person with a history of surgery related to eyeball excluding simple cataract surgery or orbital surgery such as orbital fracture Those who have more than -6D of refractive errors Those who have cataracts of ETDRS(Early Treatment Diabetic Retinopathy Study) grade 3 or higher Those who have a history of trauma around the eyeball, such as an orbital fracture, etc., Patients with active malignancy or history of malignancy, except completely treated in situ carcinoma of the cervix, completely treated and resected non-metastatic squamous of basal cell carcinoma of the skin. A person who recently(within 1 month before the clinical trial medical device is applied) suffered severe trauma or underwent major surgery Pregnant or lactating women Any other severe acute or chronic medical or psychological conditions Those who can't understand or read the consent form of this clinical trial(e.g. illiterate or foreigners) Any other cases that PI considers hard to participate in this clinical trial(e.g. heart-related problems, seizure, epilepsy. Patients transplanted metal or electronic device in head & neck. Patient suffering from unknown pain. Patients who are warned not to use out clinical trial device or is prohibited from using it.) In the case of participating in other clinical trials within 6 months prior to the time of obtaining the consent form Subjects who are not suitable for the clinical trial, are likely to be in danger when participate in the study or interfere with the interpretation of the trial results. Brain and neck implant or pacemaker including deep brain stimulation device. Implantable or wearable cardioverter defibrillator. (Dental implants are accepted.)